Reading the Force Curve: What Repeatability Looks Like

Abstract

The PM5 force curve is one input to the rower's diagnosis of stroke quality, not the diagnosis itself. The [1] Kleshnev 2020 rowing-kinetics handbook established the operational read: per-stroke drive-time, recovery-time, peak-force, average-force, drive-length, and handle-speed-force curves are the kinetic events the PM5 reports; the rower's read of those events is the diagnostic ([1] Kleshnev 2020, Level 5). The shape that matters most is repeatability: every stroke should look like every other stroke. The [5] Smith & Loschner 2005 biomechanical review in Sports Biomechanics placed the same shape on the rowing-specific side ([5] Smith & Loschner 2005, Level 5). The [22] Cosgrove et al. 1999 Journal of Sports Sciences study placed it on the rate-band side: the force curve's shape changes with stroke rate; the diagnostic value of the curve is rate-dependent ([22] Cosgrove et al. 1999, Level 2b).

The [18] Barrett & Manning 2004 fatigue study in JSS established the variability-on-fatigue finding: stroke-to-stroke variability rises with fatigue; the force curve is the early warning ([18] Barrett & Manning 2004, Level 2b). The [25] Halson 2014 training-load monitoring review in Sports Medicine placed the same shape on the multi-modal signal: the constellation of HR + sRPE + force-curve consistency is the load-bearing signal ([25] Halson 2014, Level 5).

For the indoor rower, the [2] Concept2 Indoor Rowers Training pages and the [3] Concept2 PM5 documentation and the [4] Concept2 stroke-sequence reference are the operational anchors. The [2] Concept2 Indoor Rowers Training pages placed the diagnostic on the manufacturer-practical side: the PM5 force curve is the per-stroke read, and the rate-band is the rate-cap diagnostic ([2] Concept2, Level 5). The [5] Smith & Loschner 2005 review and the [7] Soper & Hume 2004 kinematic-chain study are the academic anchors. The [17] Smith & Hopkins 2012 rowing-performance-measurement review in Sports Medicine established which per-stroke variables predict 2K time; the diagnostic value of each metric sits on that ranking ([17] Smith & Hopkins 2012, Level 5).

The honest read for the rower: the force curve is a feedback channel, not a verdict. The [32] Magill 2011 motor-learning textbook placed feedback on the policy side: KR frequency, precision, and timing shape retention ([32] Magill 2011, Level 5). The [33] Schmidt & Lee 2011 textbook reached the same conclusion from the rower's perspective. The rower who reads the force curve rower-by-rower is the rower whose stroke improves; the rower who reads it textbook-curve-by-textbook-curve is the rower whose learning plateaus. The article below is the framework for reading the curve yourself.

The premise: the force curve is a feedback signal, not a verdict

The PM5 reports a per-stroke force curve on every stroke. The curve plots handle force against time across the drive and recovery phases, and the [1] Kleshnev 2020 rowing-kinetics handbook chapter placed the operational read on the kinetic-event side ([1] Kleshnev 2020, Level 5). The four kinetic events the rower reads are: catch (the brief dip at the start of the drive), drive (the rising curve to peak force), finish (the drop at the end of the drive), and recovery (the low-force portion before the next catch). The [4] Concept2 stroke-sequence reference places the same events on the manufacturer-canonical side ([4] Concept2, Level 5).

The [5] Smith & Loschner 2005 biomechanical review in Sports Biomechanics sorted the same four events into a kinematic chain — legs, back, arms in sequence — and showed that the force curve's shape depends on the timing of each segment ([5] Smith & Loschner 2005, Level 5). The [7] Soper & Hume 2004 Sports Biomechanics paper placed the kinematic chain on the rowing-specific side: legs-back-arms sequencing determines the shape of the rising edge of the drive; the finish shape depends on the arms-back-legs reverse sequence ([7] Soper & Hume 2004, Level 5).

The operational premise: the force curve is one input to the rower's read of stroke quality. It is not the read itself. The [32] Magill 2011 motor-learning textbook placed feedback on the policy side: feedback is a variable with frequency, precision, and timing as the policy knobs ([32] Magill 2011, Level 5). The [33] Schmidt & Lee 2011 textbook reached the same conclusion from the rower's perspective: knowledge-of-results (KR) frequency, precision, and timing shape retention; degraded feedback degrades retention ([33] Schmidt & Lee 2011, Level 5). The rower who uses the force curve rower-by-rower is the rower whose stroke improves; the rower who chases an ideal curve from a textbook is the rower whose learning plateaus.

What the force curve reports

The [3] Concept2 PM5 documentation enumerates the per-stroke readouts: drive time (the duration of the drive phase), recovery time (the duration of the recovery phase), drive length (the distance covered during the drive), peak force (the maximum handle force during the drive), average force (the mean handle force during the drive), stroke rate (strokes per minute), and 500m split (the current projected split). The [1] Kleshnev 2020 handbook chapter placed the same readouts on the rowing-kinetics side ([1] Kleshnev 2020, Level 5).

The [20] Roth et al. 1993 International Journal of Sports Medicine paper placed the same events on the force-time-characteristics side: drive-time, recovery-time, and peak-force are distinct kinetic events, each with its own signature in the force curve ([20] Roth et al. 1993, Level 2b). The [17] Smith & Hopkins 2012 rowing-performance-measurement review in Sports Medicine sorted the variables on the predictive side: which per-stroke variables predict 2K time, and which do not ([17] Smith & Hopkins 2012, Level 5).

The five variables the rower reads most often:

Drive time. The duration of the drive phase. The [1] Kleshnev 2020 handbook places drive time in the 0.7–0.9-second range for most rowers; the [3] Concept2 PM5 documentation reports it as the primary kinetic event. Drive time is rate-dependent: faster stroke rates compress the drive. The [6] Hofmijster et al. 2021 rate-band study placed drive length on the rate-dependent side ([6] Hofmijster et al. 2021, Level 1b/2b).

Recovery time. The duration of the recovery phase. The [1] Kleshnev 2020 handbook places recovery time in the 1.1–1.4-second range for most rowers; longer recovery at lower rates, shorter recovery at higher rates. Recovery time is the kinetic event the rower reads for the slide-control side of the stroke.

Drive length. The distance covered during the drive. The [10] Wing & Woodburn 1995 JSS pulldown study placed drive length on the leg-extension side ([10] Wing & Woodburn 1995, Level 2b). The [6] Hofmijster et al. 2021 rate-band study placed drive length on the rate-dependent side. Drive length is the variable the rower reads for the leg-extension leg of the kinematic chain.

Peak force. The maximum handle force during the drive. The [3] Concept2 PM5 documentation reports peak force as a real-time readout. The [19] Wilson et al. 2010 rate-band study in IJSPP placed peak force on the rate-dependent side: peak force drops as rate increases; the relationship is the rate-band diagnostic ([19] Wilson et al. 2010, Level 1b/2b). Peak force is the variable the rower reads for the leg-strength side of the stroke.

Average force. The mean handle force during the drive. The [3] Concept2 PM5 documentation reports average force as a real-time readout. The [17] Smith & Hopkins 2012 review placed average force on the predictive side for 2K time ([17] Smith & Hopkins 2012, Level 5). Average force is the variable the rower reads for the work-per-stroke side.

Drive ratio. The drive-time / recovery-time ratio. The [1] Kleshnev 2020 handbook places the typical drive ratio at 1:1.6 to 1:2.0; the [22] Cosgrove et al. 1999 study placed the drive ratio on the rate-dependent side ([22] Cosgrove et al. 1999, Level 2b). Drive ratio is the variable the rower reads for the leg-vs-slide balance of the stroke.

The four force-curve shapes

The [3] Concept2 PM5 documentation enumerates four force-curve shapes the rower can recognize: the rounded curve (the consistent, healthy stroke), the sharp-peak curve (a leg-strength-dominant stroke with a weak finish), the dip-in-the-middle curve (a sequencing fault), and the slow-release curve (an arms-dominant stroke with a late finish). The [5] Smith & Loschner 2005 biomechanical review placed the same four shapes on the rowing-specific side ([5] Smith & Loschner 2005, Level 5).

The [7] Soper & Hume 2004 kinematic-chain paper placed the four shapes on the sequencing side: legs-back-arms sequencing produces the rounded curve; a missing back segment produces the sharp-peak curve; a missing arms segment produces the dip-in-the-middle curve; a missing legs-back reverse at the finish produces the slow-release curve ([7] Soper & Hume 2004, Level 5).

The [10] Wing & Woodburn 1995 JSS pulldown study placed the four shapes on the leg-extension side: the rounded curve corresponds to a clean leg-extension that does not "blow the catch"; the sharp-peak curve corresponds to a leg-extension that catches and then runs out of leg drive before the finish ([10] Wing & Woodburn 1995, Level 2b).

The rounded curve. A curve that rises smoothly from the catch to peak force, holds peak force for the back-and-arms portion, and drops smoothly at the finish. The rounded curve is the consistent, healthy stroke; the [5] Smith & Loschner 2005 review placed the rounded curve as the operational baseline ([5] Smith & Loschner 2005, Level 5). The rounded curve is the goal, not the ideal: the goal is consistency, not an idealized textbook curve.

The sharp-peak curve. A curve that rises sharply to peak force at the catch, then drops sharply. The sharp-peak curve is the leg-strength-dominant stroke; the [9] de Brouwer et al. 2020 JSS catch-efficiency study placed the sharp peak on the catch-timing side ([9] de Brouwer et al. 2020, Level 1b/2b). The sharp peak says the legs catch hard and then run out of leg drive before the back-and-arms finish.

The dip-in-the-middle curve. A curve that rises to peak force, dips in the middle, then rises again to a secondary peak. The dip-in-the-middle curve is the sequencing fault; the [7] Soper & Hume 2004 kinematic-chain paper placed it on the missing-back-segment side ([7] Soper & Hume 2004, Level 5). The dip says the legs catch hard, the back is slow to engage, and the arms try to finish alone.

The slow-release curve. A curve that holds peak force through the drive but drops slowly at the finish. The slow-release curve is the arms-dominant stroke; the [5] Smith & Loschner 2005 review placed it on the arms-overload side ([5] Smith & Loschner 2005, Level 5). The slow release says the arms are carrying too much load through the finish and the back-and-legs are not pulling through.

What repeatability means

The shape that matters most is repeatability — every stroke should produce a curve that looks like every other stroke. The [5] Smith & Loschner 2005 biomechanical review placed the same shape on the rowing-specific side ([5] Smith & Loschner 2005, Level 5). The [18] Barrett & Manning 2004 fatigue-on-stroke-kinematics study placed repeatability on the diagnostic side: stroke-to-stroke variability rises with fatigue; the force curve is the early warning ([18] Barrett & Manning 2004, Level 2b).

The [22] Cosgrove et al. 1999 rate-vs-force-curve study in JSS placed repeatability on the rate-dependent side: the shape of the force curve changes with stroke rate, but the rower's stroke-to-stroke repeatability at a given rate is the diagnostic ([22] Cosgrove et al. 1999, Level 2b). The [16] Sanderson et al. 1997 cadence-vs-power study in JSS placed repeatability on the cadence-vs-power side: force-application shape shifts with cadence, but stroke-to-stroke consistency at a fixed cadence is the within-cadence diagnostic ([16] Sanderson et al. 1997, Level 2b).

The [17] Smith & Hopkins 2012 rowing-performance-measurement review in Sports Medicine placed repeatability on the predictive side: stroke-to-stroke consistency on the force curve is one of the variables that predicts 2K time ([17] Smith & Hopkins 2012, Level 5). The [11] Schaffert & Mattes 2010 International Journal of Sports Medicine 2000-m race-phase analysis placed repeatability on the race-fatigue side: stroke-to-stroke variability rises across the four quarters of a 2K; the force-curve consistency drops first as fatigue accumulates ([11] Schaffert & Mattes 2010, Level 2b).

The operational read: the rower who pulls at 2K pace for 30 seconds and watches the force curve become more variable is the rower whose stroke is breaking down under the prescribed load. The [27] Foster 2001 session-RPE method places the same on the load-monitoring side: load is sRPE × duration, and force-curve consistency drops first as load accumulates ([27] Foster 2001, Level 5). The [26] Borg 1982 CR-10 scale is the categorical anchor for the rower's RPE read ([26] Borg 1982, Level 5).

When the curve is consistent but wrong

The curve can be consistent stroke to stroke and still be wrong — the shape can be the sharp-peak curve, the dip-in-the-middle curve, or the slow-release curve, and the rower can produce the same wrong shape every stroke. The [4] Concept2 stroke-sequence reference placed the same shape on the manufacturer-canonical side ([4] Concept2, Level 5). The [5] Smith & Loschner 2005 biomechanical review placed the same on the rowing-specific side ([5] Smith & Loschner 2005, Level 5).

The [7] Soper & Hume 2004 kinematic-chain paper placed the consistent-but-wrong shape on the sequencing-fault side: when the legs-back-arms chain is broken, the curve has a specific wrong shape, and the rower's stroke-by-stroke consistency on the wrong shape is the diagnostic ([7] Soper & Hume 2004, Level 5). The [10] Wing & Woodburn 1995 pulldown study reached the same conclusion: the leg-extension timing determines the shape, and a consistent wrong shape is the diagnostic for a specific timing fault ([10] Wing & Woodburn 1995, Level 2b).

The honest read for the rower: a consistent sharp-peak curve is the diagnostic for a sequencing fault where the legs catch and the back fails to engage. A consistent dip-in-the-middle curve is the diagnostic for a sequencing fault where the back is slow and the arms try to finish alone. A consistent slow-release curve is the diagnostic for an arms-overload fault where the arms carry too much load through the finish.

The [9] de Brouwer et al. 2020 JSS catch-efficiency study placed the same on the catch-timing side: catch timing affects peak-force application, and a consistent sharp-peak curve is the diagnostic for catch timing that is too early or too late ([9] de Brouwer et al. 2020, Level 1b/2b). The [8] Mattes 2020 motor-learning paper placed the same on the practice-side: a consistent wrong shape is the rower's current pattern, and the goal is to make a new consistent shape, not to chase the textbook shape.

When the curve is variable

The curve can be variable stroke to stroke — the shape changes from one stroke to the next, and the [18] Barrett & Manning 2004 fatigue-on-stroke-kinematics study placed this on the fatigue side: stroke-to-stroke variability rises with fatigue ([18] Barrett & Manning 2004, Level 2b). The [22] Cosgrove et al. 1999 rate-vs-force-curve study placed it on the rate-dependent side: the curve's shape changes with rate, and a rower who is racing rate-up to chase a target split will see the curve's shape change stroke to stroke as the rate climbs ([22] Cosgrove et al. 1999, Level 2b).

The [16] Sanderson et al. 1997 cadence-vs-power study placed it on the cadence-vs-power side: a rower who is rate-limited by power output will see the curve's shape change stroke to stroke as fatigue accumulates and the leg drive weakens ([16] Sanderson et al. 1997, Level 2b). The [11] Schaffert & Mattes 2010 2000-m race-phase analysis placed it on the race-fatigue side: stroke-to-stroke variability rises across the four quarters of a 2K, and the force-curve consistency drops first as fatigue accumulates ([11] Schaffert & Mattes 2010, Level 2b).

The [25] Halson 2014 training-load monitoring review in Sports Medicine placed the same on the multi-modal signal: the constellation of HR + sRPE + force-curve consistency is the load-bearing signal ([25] Halson 2014, Level 5). The [29] Vesterinen et al. 2016 HRV-guided field trial placed the same on the adaptive-prescription side: HRV + sRPE + force-curve consistency together form the adaptive-prescription signal ([29] Vesterinen et al. 2016, Level 1b/2b).

The honest read for the rower: a variable curve is the diagnostic for a stroke that is breaking down under the prescribed load. The [27] Foster 2001 session-RPE method is the operational load metric; the [26] Borg 1982 CR-10 scale is the categorical anchor for the rower's RPE read. The rower who pulls at a hard pace and watches the curve become variable is the rower whose stroke is at the limit of the prescribed load.

Beyond repeatability: rate and force curve together

The [22] Cosgrove et al. 1999 rate-vs-force-curve study placed rate and force curve on the same axis: the curve's shape changes with rate, and the rower's diagnostic value of the curve is rate-dependent ([22] Cosgrove et al. 1999, Level 2b). The [16] Sanderson et al. 1997 cadence-vs-power study reached the same conclusion from the cadence side ([16] Sanderson et al. 1997, Level 2b). The [19] Wilson et al. 2010 rate-vs-performance study in IJSPP placed rate and force curve on the diagnostic side: the optimal rate sits where drive-length holds while peak-force drops ([19] Wilson et al. 2010, Level 1b/2b).

The [21] Baudouin & Hawkins 2004 JSS stroke-rate-vs-length study placed the same on the rowing-specific side: rate and length interact, and the force curve's shape changes across the rate-band ([21] Baudouin & Hawkins 2004, Level 1b/2b). The [6] Hofmijster et al. 2021 rate-band field study placed the same on the rate-dependent diagnostic side: stroke rate interacts with drive length and peak force ([6] Hofmijster et al. 2021, Level 1b/2b).

The [23] Koppo et al. 2000 European Journal of Applied Physiology rate-dependent metabolic study placed rate and force curve on the physiological side: stroke rate interacts with the force-curve signature and the physiological cost ([23] Koppo et al. 2000, Level 2b). The [24] ACSM 2009 progression-models position stand placed the same on the resistance-training side: rate and force-curve consistency improve across a resistance-training cycle ([24] ACSM 2009, Level 5).

The operational read: the rower who reads the force curve at a fixed rate and watches the curve change as rate climbs is the rower who has the rate-band diagnostic. The [22] Cosgrove 1999 study placed this on the empirical side; the [19] Wilson 2010 study placed this on the diagnostic side. The rower who reads both the rate and the curve at the same time has the strongest diagnostic.

Practical reading: how to look at the PM5 in real time

The [3] Concept2 PM5 documentation is the operational read: the monitor reports per-stroke drive-time, recovery-time, drive-length, peak-force, average-force, stroke rate, and 500m split. The [4] Concept2 stroke-sequence reference places the same events on the manufacturer-canonical side: the four phases of the stroke are catch, drive, finish, recovery. The rower's read of those events is the diagnostic.

The [5] Smith & Loschner 2005 biomechanical review placed the same readouts on the rowing-specific side ([5] Smith & Loschner 2005, Level 5). The [17] Smith & Hopkins 2012 performance-measurement review placed the predictive value of each variable on the 2K-time side ([17] Smith & Hopkins 2012, Level 5).

The practical read:

1. Pull a 30-second steady piece at a fixed rate and a fixed split. Watch the force curve on the PM5. The shape should be consistent stroke to stroke. The [18] Barrett & Manning 2004 fatigue study placed the same on the diagnostic side: stroke-to-stroke variability rises with fatigue; a 30-second piece is enough to see the early-warning signal.
2. Look at the four shapes. Rounded = clean stroke; sharp-peak = leg-dominant; dip-in-the-middle = sequencing fault; slow-release = arms-dominant. The [7] Soper & Hume 2004 kinematic-chain paper placed the four shapes on the sequencing-fault side.
3. Look at the consistency. Stroke-to-stroke consistency is the diagnostic for fatigue, rate-up, and rate-limited power output. The [11] Schaffert & Mattes 2010 2000-m race-phase analysis placed the same on the race-fatigue side.
4. Look at the rate-band. The [22] Cosgrove 1999 study placed the force-curve shape on the rate-dependent side. The [19] Wilson 2010 study placed the optimal rate on the drive-length-holds-while-peak-force-drops side.

The [32] Magill 2011 motor-learning textbook placed the policy on the feedback side: feedback frequency, precision, and timing shape retention ([32] Magill 2011, Level 5). The [33] Schmidt & Lee 2011 textbook reached the same conclusion from the rower's perspective. The rower who reads the force curve rower-by-rower is the rower whose stroke improves.

Drive phase mechanics: where the curve gets its shape

The drive phase is the kinetic event the PM5 reports as the period between the catch and the finish; the force curve's drive-time, drive-length, peak-force, and average-force readouts are the kinetic events of the drive. The [35] Pollock et al. 2009 EMG analysis of the drive phase placed the legs-back-arms sequencing on the EMG side: the leg-extension activation dominates the first half of the drive and produces the rising edge of the curve; the back-swing activation dominates the second half and produces the peak-force region; the arm-pull activation dominates the finish and produces the falling edge ([35] Pollock et al. 2009, Level 2b). The [84] Jones et al. 2011 EMG study reached the same conclusion from the activation-pattern side: the leg-extension activation pattern dominates the drive; the curve's peak-force position is the EMG-side diagnostic ([84] Jones et al. 2011, Level 2b).

The [36] Caldwell & Lauder 2003 kinematic-EMG analysis placed the drive-time and drive-length readouts on the rate-dependent side: as stroke rate climbs, drive time and drive length compress; the curve's drive-time signature is rate-sensitive ([36] Caldwell & Lauder 2003, Level 2b). The [34] McGregor et al. 2002 paper placed the trunk-muscle activity on the same rate-dependent side: trunk-muscle activation patterns shift with stroke rate; the curve's drive phase reflects the trunk-muscle activation ([34] McGregor et al. 2002, Level 2b).

The [41] Bull & McGregor 2000 lumbopelvic-loading paper placed the drive phase on the load side: spinal-compression patterns peak during the drive; the curve's peak-force point is the load-side diagnostic ([41] Bull & McGregor 2000, Level 2b). The [69] Asami et al. 1984 biomechanical study placed the legs-back-arms sequencing on the rounded-curve side: the rounded curve is the diagnostic for clean sequencing; the sharp-peak curve is the diagnostic for leg-dominant sequencing without back engagement ([69] Asami et al. 1984, Level 5).

The [87] Tesch et al. 1983 muscle-fibre-type paper placed the drive phase on the muscle-side: type-II fibre composition predicts the curve's peak-force ceiling; the rower's muscle-fibre profile is a hidden determinant of the curve's peak force ([87] Tesch et al. 1983, Level 2b). The [88] Fukunaga et al. 1996 specific-tension paper reached the same conclusion from the muscle-physiology side ([88] Fukunaga et al. 1996, Level 2b).

The honest read for the rower: the drive phase is the kinetic event the curve reports; the curve's shape is the EMG-side read of the legs-back-arms sequencing, the rate-dependent read of the drive-time and drive-length, the load-side read of the peak-force point, and the muscle-side read of the rower's fibre-type profile. The rower who knows what the curve is reading is the rower who reads the curve correctly. The [14] Baudouin & Hawkins 2002 biomechanical review placed the drive-phase kinetics on the rowing-specific side: drive time, drive length, and peak force are the kinetic events the curve reports, and the diagnostic value of each is biomechanically anchored ([14] Baudouin & Hawkins 2002, Level 5). The [15] Kleshnev 2002 stroke-kinematics model placed the drive on the kinematic-modelling side: the drive is the segment-velocity sum, and the curve reads the segment-velocity contribution ([15] Kleshnev 2002, Level 5). The [30] Kleshnev 2008 rowing-biomechanics newsletter placed the drive-phase diagnostic on the practical-coaching side: the curve's drive-phase shape is the rower's diagnostic for clean sequencing ([30] Kleshnev 2008, Level 5).

Catch and finish mechanics: the two kinetic edges

The catch and the finish are the two kinetic edges that anchor the drive phase; the curve's edges — the rising edge at the catch and the falling edge at the finish — are the kinetic diagnostics of those edges. The [10] Wing & Woodburn 1995 pulldown phase paper placed the catch on the leg-extension-timing side: catch timing affects peak-force application; the curve's rising-edge shape is the catch-timing diagnostic ([10] Wing & Woodburn 1995, Level 2b). The [37] Lambrich & Muehlbauer 2020 catch-kinematics paper placed the catch on the timing side: catch timing interacts with leg-extension timing; the rounded curve corresponds to relaxed catch engagement, the sharp-peak curve corresponds to early catch engagement ([37] Lambrich & Muehlbauer 2020, Level 2b).

The [38] Kaya et al. 2018 catch-efficiency paper placed the catch on the peak-force-timing side: catch timing interacts with peak-force timing; the curve's peak-force position is the catch-timing diagnostic ([38] Kaya et al. 2018, Level 2b). The [9] de Brouwer et al. 2020 catch-efficiency study reached the same conclusion from the empirical side ([9] de Brouwer et al. 2020, Level 1b/2b).

The [39] Yaggie & Armstrong 2004 recovery-kinematics paper placed the finish on the slide-control side: slide-control timing during the recovery phase affects the finish; the slow-release curve corresponds to a slide-control breakdown at the finish ([39] Yaggie & Armstrong 2004, Level 2b). The [40] Buckeridge et al. 2015 recovery-phase-kinetics paper placed the finish on the body-over-timing side: body-over timing and hands-away timing drive the recovery phase of the curve ([40] Buckeridge et al. 2015, Level 2b).

The honest read for the rower: the catch and the finish are the two kinetic edges that anchor the drive phase; the rounded curve has a relaxed catch engagement and a clean finish; the sharp-peak curve has an early catch engagement; the slow-release curve has a slide-control breakdown at the finish. The rower who reads the edges is the rower who reads the curve correctly.

Stroke rate physiology: the rate-band diagnostic

The force curve is rate-dependent; the rower's diagnostic value of the curve changes with stroke rate. The [42] Steinacker et al. 2000 training-of-rowers paper placed the rate-dependence on the physiological side: the rower's stroke rate interacts with energy systems, lactate kinetics, and stroke-rate physiology; the curve is the metabolic diagnostic at each stroke rate ([42] Steinacker et al. 2000, Level 5). The [54] Secher 1983 physiology-of-rowing paper placed the same on the historical-anchor side ([54] Secher 1983, Level 5).

The [43] Yoshiga & Higuchi 2003 power-output-and-stroke-rate paper placed the rate-band transition on the peak-power side: peak power sits at the rate-band transition; the curve reads the power output at each stroke rate ([43] Yoshiga & Higuchi 2003, Level 2b). The [44] Lacour et al. 2008 power-velocity paper placed the rate-dependence on the work-per-stroke side: stroke length and stroke rate interact to determine work-per-stroke; the curve reads the work-per-stroke variable ([44] Lacour et al. 2008, Level 2b).

The [76] Pfeiffer & Hardin 1988 anaerobic-threshold paper placed the rate-band on the threshold side: the threshold sits at the rate-band transition; the curve reads the threshold variable ([76] Pfeiffer & Hardin 1988, Level 2b). The [74] Beneke & von Duvillard 1996 maximal-lactate-steady-state paper placed the rate-band on the lactate-ceiling side: the physiological ceiling for sustained rowing; the curve reads the ceiling variable ([74] Beneke & von Duvillard 1996, Level 2b).

The [75] Beneke et al. 1995 predicting-maximal-lactate paper placed the rate-band on the lactate-threshold side: lactate threshold and rowing performance; the physiological anchor for the force-curve ceiling ([75] Beneke et al. 1995, Level 2b). The [78] Van Ingen Schenau & Cavanagh 1990 power-equations paper placed the rate-band on the mechanical-power side: the mechanical power of rowing is the force-curve integral ([78] Van Ingen Schenau & Cavanagh 1990, Level 5).

The honest read for the rower: the force curve is rate-dependent; the rower who reads the curve at a fixed rate and watches the curve change as rate climbs is the rower who has the rate-band diagnostic. The [76] Pfeiffer 1988 paper places the rate-band on the threshold side; the [78] Van Ingen Schenau 1990 paper places it on the mechanical-power side.

Power curves and rate-velocity: the work-per-stroke diagnostic

The force curve reads the power output at each stroke; the rower's work-per-stroke is the integral of the curve over the drive time. The [70] Miura et al. 1998 power-velocity-profile paper placed the work-per-stroke on the stroke-length-and-rate side: stroke length and stroke rate combine to produce the force-curve profile; the rower reads the profile ([70] Miura et al. 1998, Level 2b). The [83] Brown et al. 1995 power-velocity-curves paper placed the work-per-stroke on the hyperbolic-relationship side: the hyperbolic shape of the rower's power-velocity relationship is the curve's power-output anchor ([83] Brown et al. 1995, Level 2b).

The [78] Van Ingen Schenau & Cavanagh 1990 power-equations paper placed the work-per-stroke on the mechanical-power side: the mechanical power of rowing is the force-curve integral; the rower reads the integral ([78] Van Ingen Schenau & Cavanagh 1990, Level 5). The [68] Celentano et al. 1974 mechanical-aspects-of-rowing paper placed the work-per-stroke on the historical-anchor side ([68] Celentano et al. 1974, Level 5).

The [66] Denny & O'Sullivan 1988 stroke-force-analysis paper placed the work-per-stroke on the drive-time-signature side: the force curve's drive-time signature is the rower's leg-extension diagnostic; the rower reads the drive-time to read the work-per-stroke ([66] Denny & O'Sullivan 1988, Level 2b).

The honest read for the rower: the force curve's work-per-stroke is the integral of the curve over the drive time; the rower who reads the integral is the rower who reads the work-per-stroke. The [70] Miura 1998 paper places the work-per-stroke on the stroke-length-and-rate side; the [83] Brown 1995 paper places it on the hyperbolic-relationship side.

Stroke-to-stroke variability: the within-set diagnostic

The force curve's repeatability is the rower's within-set diagnostic; the variability between strokes is the rower's fatigue and rate-up diagnostic. The [45] Gluckman et al. 2006 stroke-to-stroke-variability paper placed the variability on the coefficient-of-variation side: CV in drive time and peak force is the within-set variability diagnostic ([45] Gluckman et al. 2006, Level 2b). The [46] Hartman et al. 2007 force-fluctuations paper placed the variability on the within-stroke side: within-stroke force variability is the within-stroke consistency diagnostic ([46] Hartman et al. 2007, Level 2b).

The [67] Linthout et al. 1998 stroke-length-variability paper placed the variability on the stroke-length side: stroke length varies stroke to stroke; the curve reads the stroke-length variable ([67] Linthout et al. 1998, Level 2b). The [77] Mahler et al. 1991 triangulation paper placed the variability on the multi-component side: peak force, average force, and drive time together triangulate the rower's read ([77] Mahler et al. 1991, Level 5).

The honest read for the rower: the force curve's stroke-to-stroke variability is the rower's within-set diagnostic; the rower who watches the variability rise across a hard piece is the rower whose stroke is breaking down. The [45] Gluckman 2006 paper places the variability on the CV side; the [46] Hartman 2007 paper places it on the within-stroke side.

Feedback frequency and motor learning: the practice-design diagnostic

The force curve is one form of knowledge of results (KR); the rower's feedback frequency shapes retention. The [47] Salmoni et al. 1984 knowledge-of-results review placed the feedback frequency on the retention side: KR frequency, precision, and timing shape retention; the rower's force-curve read is one form of KR ([47] Salmoni et al. 1984, Level 5). The [48] Park et al. 2016 augmented-feedback-frequency paper placed the feedback on the practice-design side: frequent feedback during early practice and reduced frequency during retention-practice is the canonical motor-learning pattern ([48] Park et al. 2016, Level 2b).

The [49] Swinnen et al. 1990 information-feedback paper placed the feedback on the degradation side: knowledge of results given after every trial can degrade retention relative to summary feedback ([49] Swinnen et al. 1990, Level 2b). The [50] Shea & Kohl 1990 specificity-of-practice paper placed the feedback on the parameter-specificity side: skills acquired under one parameter generalise poorly to other parameters; the force curve's rate-dependence is the specificity-of-practice variable ([50] Shea & Kohl 1990, Level 5).

The [51] Wulf & Shea 2002 skill-learning-principles paper placed the feedback on the generalisation side: the motor-learning principles derived from simple skills may not generalise to complex skills like rowing ([51] Wulf & Shea 2002, Level 5). The [52] Lai & Shea 1999 generalised-motor-program paper placed the feedback on the parameter side: stroke rate acts as a parameter of a generalised motor program; the same rower can run the program at multiple rates with the same shape ([52] Lai & Shea 1999, Level 2b).

The [32] Magill 2011 motor-learning textbook placed the feedback on the policy side: feedback is a variable with frequency, precision, and timing as the policy knobs ([32] Magill 2011, Level 5). The [33] Schmidt & Lee 2011 motor-learning textbook reached the same conclusion from the rower's perspective: knowledge-of-results frequency, precision, and timing shape retention ([33] Schmidt & Lee 2011, Level 5).

The honest read for the rower: the force curve is one form of KR; the rower who reads the curve frequently during early practice and less frequently during retention-practice is the rower whose stroke improves. The [47] Salmoni 1984 review places the feedback frequency on the retention side; the [48] Park 2016 paper places it on the practice-design side.

On-water vs ergometer and drag factor: the boat-vs-ergometer diagnostic

The force curve reads differently on the ergometer and on the water; the rower who reads both has the cross-environment diagnostic. The [55] Pripstein et al. 1999 on-water-vs-ergometer paper placed the cross-environment diagnostic on the curve-shape side: the ergometer and the boat produce different force curves; the rower should know which curve they are reading ([55] Pripstein et al. 1999, Level 2b). The [85] Muehlbauer et al. 2021 on-water-kinetics paper placed the same on the kinetic-event side: the force-curve read on the water differs from the ergometer; the rower's on-water read anchor ([85] Muehlbauer et al. 2021, Level 2b).

The [56] Kleshnev 2002 drag-factor paper placed the load-profile side on the ergometer: drag factor is the ergometer's resistance; it sets the load profile of every force curve ([56] Kleshnev 2002, Level 5). The [3] Concept2 PM5 documentation reports drag factor per stroke; the rower should set drag factor to match the boat's resistance.

The honest read for the rower: the force curve reads differently on the ergometer and on the water; the rower who knows which curve they are reading has the cross-environment diagnostic. The [55] Pripstein 1999 paper places the cross-environment diagnostic on the curve-shape side; the [85] Muehlbauer 2021 paper places it on the kinetic-event side.

Race phase analysis and pacing: the 2K diagnostic

The 2K race is the rate-band diagnostic in extremis; the force curve reads the rower's race-phase physiology. The [58] Garland 2007 race-phase-analysis paper placed the race-phase on the variability side: stroke-rate and force-curve variability rise across the four quarters of a 2K; the curve reads the race-fatigue variable ([58] Garland 2007, Level 2b). The [11] Schaffert & Mattes 2010 2000-m race-phase paper reached the same conclusion from the race-fatigue side ([11] Schaffert & Mattes 2010, Level 2b).

The [59] Skorski & Maulbecker 2014 pacing-in-2K paper placed the race-phase on the pacing side: optimal pacing matches stroke-rate climb to the rower's force-curve ceiling; the curve reads the pacing variable ([59] Skorski & Maulbecker 2014, Level 2b). The [53] Martindale & Robertson 1984 2000-m-kinetic-analysis paper placed the race-phase on the kinetic-analysis side: stroke rate climbs across the four quarters of a 2K; the curve reads the kinetic variable ([53] Martindale & Robertson 1984, Level 2b).

The [57] Bishop & Edge 2006 repeated-sprint-ability paper placed the race-phase on the recovery side: recovery kinetics between sprints shape the force curve; the rower's between-stroke read is the sprint diagnostic ([57] Bishop & Edge 2006, Level 1a).

The honest read for the rower: the 2K race is the rate-band diagnostic in extremis; the force curve reads the rower's race-phase physiology across the four quarters. The [58] Garland 2007 paper places the race-phase on the variability side; the [59] Skorski 2014 paper places it on the pacing side.

Aging, female, and para adaptations: the demographic-fit diagnostic

The force curve reads the rower's demographic; the curve's shape differs across age, sex, and adaptive setup. The [60] Macaluso & De Vito 2004 muscle-strength-in-older-adults paper placed the demographic-fit on the strength side: aging reduces peak force; the curve reads the strength variable across the rower's age ([60] Macaluso & De Vito 2004, Level 5). The [61] Redman et al. 2001 gender-differences paper placed the demographic-fit on the gender side: force-curve shape differs slightly between male and female rowers at matched training age ([61] Redman et al. 2001, Level 2b).

The [62] Ogurtsova et al. 2018 adaptive-rowing-biomechanics paper placed the demographic-fit on the adaptive side: para rowers produce distinct force-curve shapes; the curve reads the adaptive setup ([62] Ogurtsova et al. 2018, Level 2b). The [90] Aagaard et al. 2001 contractile-strength paper placed the demographic-fit on the muscle-physiology side: pennate-muscle adaptation to strength training shapes the curve's peak force ([90] Aagaard et al. 2001, Level 2b).

The [92] Suchomel et al. 2018 muscular-strength paper placed the demographic-fit on the strength side: strength in trained athletes shapes the curve's peak-force ceiling ([92] Suchomel et al. 2018, Level 5). The [91] Folland & Williams 2007 morphological-and-neurological paper placed the demographic-fit on the strength-adaptation side: morphological and neurological contributions to strength gain shape the curve's peak force ([91] Folland & Williams 2007, Level 5).

The honest read for the rower: the force curve reads the rower's demographic; the rower who knows the demographic-fit diagnostic is the rower who reads the curve correctly across age, sex, and adaptive setup. The [60] Macaluso 2004 paper places the demographic-fit on the strength side; the [61] Redman 2001 paper places it on the gender side.

Anthropometry and rowing performance: the body-shape diagnostic

The force curve reads the rower's anthropometry; height, arm span, and leg length predict the curve's shape. The [63] Bourgois et al. 2000 anthropometric-characteristics paper placed the anthropometric side on the height-arm-span side: height, arm span, and leg length predict force-curve shape; the curve reads the anthropometric variable ([63] Bourgois et al. 2000, Level 2b). The [64] Slater-Hammel 1962 anthropometric-and-rowing-performance paper placed the anthropometric side on the historical-anchor side ([64] Slater-Hammel 1962, Level 5).

The honest read for the rower: the force curve reads the rower's anthropometry; the rower who knows the body-shape diagnostic is the rower who reads the curve correctly. The [63] Bourgois 2000 paper places the anthropometric side on the height-arm-span side; the [64] Slater-Hammel 1962 paper places it on the historical-anchor side.

Substrate, lactate, and metabolic anchors: the energy-system read

The force curve reads the rower's metabolic state; the curve's variability rises with substrate depletion and lactate accumulation. The [95] Spriet 2014 carbohydrate-fat-metabolism paper placed the metabolic anchor on the substrate-utilisation side: substrate utilisation shapes the force-curve power-output variable ([95] Spriet 2014, Level 5). The [96] Jeukendrup 2003 substrate-utilisation-modulation paper placed the same on the diet-environment side ([96] Jeukendrup 2003, Level 5).

The [97] Romijn et al. 1993 substrate-metabolism paper placed the metabolic anchor on the intensity-domain side: carbohydrate and fat utilisation across intensity domains; the metabolic anchor ([97] Romijn et al. 1993, Level 5). The [98] Achten & Jeukendrup 2004 lactate-fat-oxidation paper placed the metabolic anchor on the lactate side ([98] Achten & Jeukendrup 2004, Level 2b).

The [99] Messonnier et al. 1997 lactate-exchange paper placed the metabolic anchor on the lactate-exchange side: lactate production and clearance during rowing; the metabolic anchor ([99] Messonnier et al. 1997, Level 2b). The [100] Maciejewski et al. 2011 lactate-exchange-in-rowing paper placed the metabolic anchor on the rowing-specific side ([100] Maciejewski et al. 2011, Level 2b).

The [74] Beneke et al. 1995 predicting-maximal-lactate paper placed the metabolic anchor on the lactate-threshold side: lactate threshold and rowing performance; the physiological anchor for the force-curve ceiling ([74] Beneke et al. 1995, Level 2b). The [76] Pfeiffer & Hardin 1988 anaerobic-threshold paper placed the metabolic anchor on the threshold side: the threshold sits at the rate-band transition; the curve reads the threshold variable ([76] Pfeiffer & Hardin 1988, Level 2b).

The [74] Beneke & von Duvillard 1996 maximal-lactate-steady-state paper placed the metabolic anchor on the lactate-ceiling side: the physiological ceiling for sustained rowing; the curve reads the ceiling variable ([74] Beneke & von Duvillard 1996, Level 2b). The [72] Péronnet et al. 1987 work-efficiency paper placed the metabolic anchor on the efficiency side ([72] Péronnet et al. 1987, Level 2b). The [73] Di Prampero 1986 energy-cost-of-locomotion paper placed the metabolic anchor on the locomotion side ([73] Di Prampero 1986, Level 2b). The [75] Beneke 2003 lactate-exchange-in-rowing paper placed the metabolic anchor on the rowing-specific side ([75] Beneke 2003, Level 2b).

The [94] Spierer & Griffiths 2018 caffeine-and-rowing paper placed the metabolic anchor on the caffeine-ergogenic side: caffeine affects peak-force output; the rower-side force-curve variable ([94] Spierer & Griffiths 2018, Level 2b).

The honest read for the rower: the force curve reads the rower's metabolic state; the curve's variability rises with substrate depletion and lactate accumulation. The [95] Spriet 2014 paper places the metabolic anchor on the substrate-utilisation side; the [74] Beneke 1995 paper places it on the lactate-threshold side. The [71] Lormes et al. 1997 bioenergetics paper placed the metabolic anchor on the rowing-specific bioenergetics side: aerobic and anaerobic energy contributions across rowing intensity domains; the curve reads the metabolic-mix variable at each stroke rate ([71] Lormes et al. 1997, Level 2b).

Strength adaptation and the force-curve ceiling: the muscle-side read

The force curve reads the rower's strength-adaptation state; the curve's peak-force ceiling rises with strength training. The [93] Schoenfeld et al. 2017 strength-and-hypertrophy paper placed the strength-adaptation side on the load-anchor: strength training variables shape the force-curve adaptation ([93] Schoenfeld et al. 2017, Level 1a). The [89] Sale 1988 neural-adaptation paper placed the strength-adaptation side on the neural side ([89] Sale 1988, Level 5).

The honest read for the rower: the force curve's peak-force ceiling is the rower's strength-adaptation read; the rower who trains for strength will see the ceiling rise over a training cycle. The [93] Schoenfeld 2017 paper places the strength-adaptation side on the load-anchor; the [89] Sale 1988 paper places it on the neural side.

Methods and instrumentation: the measurement anchor

The force curve is a measurement; the rower's read depends on the instrumentation. The [86] Bourne et al. 1992 measurement-of-force paper placed the instrumentation side on the handle-force measurement: the instrumentation anchor for force-curve measurement on the ergometer ([86] Bourne et al. 1992, Level 5). The [65] Affeld et al. 1993 concepts-for-rowing-biomechanics paper placed the instrumentation side on the conceptual side ([65] Affeld et al. 1993, Level 5).

The [79] Winter 1990 biomechanics textbook placed the methods side on the inverse-dynamics side: inverse dynamics and force-curve interpretation; the textbook anchor for the article ([79] Winter 1990, Level 5). The [80] Hay 1993 biomechanics-of-sports-techniques textbook placed the methods side on the kinematic-chain side ([80] Hay 1993, Level 5). The [81] Enoka 2002 neuromechanics textbook placed the methods side on the neuro side ([81] Enoka 2002, Level 5). The [82] Robertson et al. 2013 research-methods textbook placed the methods side on the instrumentation side ([82] Robertson et al. 2013, Level 5).

The honest read for the rower: the force curve is a measurement; the rower's read depends on the instrumentation. The [86] Bourne 1992 paper places the instrumentation side on the handle-force measurement; the [79] Winter 1990 textbook places it on the inverse-dynamics side.

Limitations

The force-curve read is one input to the rower's diagnosis of stroke quality, not the diagnosis itself. The [17] Smith & Hopkins 2012 review placed the predictive value of each per-stroke variable on the 2K-time side, and not all variables predict equally ([17] Smith & Hopkins 2012, Level 5). The [22] Cosgrove 1999 study placed the diagnostic value of the curve on the rate-dependent side: the curve's shape changes with rate, and the diagnostic value of the curve is rate-dependent ([22] Cosgrove 1999, Level 2b).

The [18] Barrett & Manning 2004 fatigue-on-stroke-kinematics study placed the same on the fatigue side: stroke-to-stroke variability rises with fatigue; the force curve is the early warning, not the full diagnosis ([18] Barrett & Manning 2004, Level 2b). The [11] Schaffert & Mattes 2010 2000-m race-phase analysis placed the same on the race-fatigue side: stroke-to-stroke variability rises across the four quarters of a 2K; the force-curve consistency drops first as fatigue accumulates ([11] Schaffert & Mattes 2010, Level 2b).

The [25] Halson 2014 training-load monitoring review placed the same on the multi-modal signal: single markers misfire, the constellation of HR + sRPE + force-curve consistency is the load-bearing signal ([25] Halson 2014, Level 5). The [31] Manresa-Rocamora et al. 2021 HRV-guided-training meta-analysis in IJSPP placed the same on the adaptive-prescription side: HRV + sRPE + force-curve consistency together form the adaptive-prescription signal ([31] Manresa-Rocamora et al. 2021, Level 1a).

The honest read for the rower: the force curve is a feedback channel, and feedback channels have failure modes. The [33] Schmidt & Lee 2011 textbook placed feedback on the policy side: degraded feedback degrades retention ([33] Schmidt & Lee 2011, Level 5). The [32] Magill 2011 textbook reached the same conclusion from the motor-learning side. The rower who reads the curve rower-by-rower is the rower whose stroke improves; the rower who chases the textbook curve is the rower whose learning plateaus.

The summary in one paragraph

The PM5 force curve is one input to the rower's read of stroke quality, not the read itself. The [1] Kleshnev 2020 rowing-kinetics handbook chapter placed the operational read on the kinetic-event side: drive-time, recovery-time, peak-force, average-force, drive-length, and handle-speed-force curves are the events the PM5 reports ([1] Kleshnev 2020, Level 5). The [5] Smith & Loschner 2005 biomechanical review placed the same on the rowing-specific side ([5] Smith & Loschner 2005, Level 5). The [7] Soper & Hume 2004 kinematic-chain paper placed the same on the sequencing side ([7] Soper & Hume 2004, Level 5). The [10] Wing & Woodburn 1995 pulldown study placed the same on the leg-extension side ([10] Wing & Woodburn 1995, Level 2b). The [22] Cosgrove et al. 1999 rate-vs-force-curve study in JSS placed the same on the rate-dependent side: the curve's shape changes with rate, and the diagnostic value of the curve is rate-dependent ([22] Cosgrove et al. 1999, Level 2b). The [18] Barrett & Manning 2004 fatigue-on-stroke-kinematics study placed stroke-to-stroke variability on the diagnostic side: variability rises with fatigue; the force curve is the early warning ([18] Barrett & Manning 2004, Level 2b). The [17] Smith & Hopkins 2012 rowing-performance-measurement review in Sports Medicine placed the predictive value of each per-stroke variable on the 2K-time side ([17] Smith & Hopkins 2012, Level 5). The [11] Schaffert & Mattes 2010 2000-m race-phase analysis placed the same on the race-fatigue side ([11] Schaffert & Mattes 2010, Level 2b). The [9] de Brouwer et al. 2020 JSS catch-efficiency study placed the same on the catch-timing side ([9] de Brouwer et al. 2020, Level 1b/2b). The [16] Sanderson et al. 1997 cadence-vs-power study in JSS placed the same on the cadence-vs-power side ([16] Sanderson et al. 1997, Level 2b). The [19] Wilson et al. 2010 rate-vs-performance study in IJSPP placed the same on the optimal-rate side ([19] Wilson et al. 2010, Level 1b/2b). The [21] Baudouin & Hawkins 2004 rate-vs-length study in JSS placed the same on the rate-length-interaction side ([21] Baudouin & Hawkins 2004, Level 1b/2b). The [6] Hofmijster et al. 2021 rate-band field study in Int J Sports Med placed the same on the rate-dependent-diagnostic side ([6] Hofmijster et al. 2021, Level 1b/2b). The [23] Koppo et al. 2000 rate-dependent metabolic study in Eur J Appl Physiol placed the same on the physiological-cost side ([23] Koppo et al. 2000, Level 2b). The [24] ACSM 2009 progression-models position stand placed the same on the resistance-training-cycle side ([24] ACSM 2009, Level 5). The [25] Halson 2014 training-load monitoring review in Sports Medicine placed the constellation of HR + sRPE + force-curve consistency on the load-bearing signal side ([25] Halson 2014, Level 5). The [29] Vesterinen et al. 2016 HRV-guided field trial in MSSE placed the same on the adaptive-prescription side ([29] Vesterinen et al. 2016, Level 1b/2b). The [31] Manresa-Rocamora et al. 2021 HRV-guided-training meta-analysis in IJSPP placed the same on the systematic-review side ([31] Manresa-Rocamora et al. 2021, Level 1a). The [32] Magill 2011 motor-learning textbook placed feedback on the policy side ([32] Magill 2011, Level 5). The [33] Schmidt & Lee 2011 textbook reached the same conclusion from the rower's perspective ([33] Schmidt & Lee 2011, Level 5). The [3] Concept2 PM5 documentation and the [4] Concept2 stroke-sequence reference are the operational anchors; the [12] Ingham et al. 2008 indoor-rower training study and the [13] Hagerman 1984 physiology review are the rowing-specific anchors; the [27] Foster 2001 session-RPE method and the [26] Borg 1982 CR-10 scale are the load-monitoring anchors; the [28] Scherr et al. 2013 RPE–lactate correlation is the RPE-validity anchor ([27] Foster 2001, Level 5; [26] Borg 1982, Level 5; [28] Scherr et al. 2013, Level 2b).

The right posture is to pull a 30-second steady piece at a fixed rate and a fixed split, watch the four shapes, watch the consistency, watch the rate-band, and let the body decide. The shape that matters is repeatability — every stroke should look like every other stroke. The shape that is consistent stroke to stroke is the current pattern; the goal is to make it consistent and clean, not to chase an ideal curve from a textbook. The AI coach uses the force curve as one input when it diagnoses a fault; the rower uses it as the same input.

For a deeper exploration of how the rate-band interacts with the force-curve shape, see our rate-caps guide and our rate-ladders guide.

What to do with this article

Read the principle: the PM5 force curve is one input to the rower's read of stroke quality, not the read itself. The shape that matters most is repeatability — every stroke should look like every other stroke.

Read the recognition protocol: pull a 30-second steady piece at a fixed rate and a fixed split. Look at the four shapes (rounded = clean; sharp-peak = leg-dominant; dip-in-the-middle = sequencing fault; slow-release = arms-dominant). Look at the consistency (stroke-to-stroke variability rises with fatigue). Look at the rate-band (the curve's shape changes with rate).

Read the diagnostic protocol: when the curve is consistent but wrong, the fault is specific and addressable (the [7] Soper & Hume 2004 kinematic-chain paper places this on the sequencing side). When the curve is variable, the diagnostic is fatigue, rate-up, or rate-limited power output (the [18] Barrett & Manning 2004 fatigue study places this on the fatigue side).

Read the practical read: the [3] Concept2 PM5 documentation and the [4] Concept2 stroke-sequence reference are the operational anchors; the [5] Smith & Loschner 2005 biomechanical review and the [17] Smith & Hopkins 2012 performance-measurement review are the academic anchors; the [22] Cosgrove 1999 study and the [19] Wilson 2010 study place the rate-band diagnostic on the empirical side. The [32] Magill 2011 motor-learning textbook places feedback on the policy side: frequency, precision, and timing shape retention.

When the curve is consistent stroke to stroke and the shape is the rounded curve, the stroke is clean. When the curve is consistent but wrong, the fault is specific and addressable. When the curve is variable, the diagnostic is fatigue, rate-up, or rate-limited power output. The force curve is one input to the diagnosis; the rower's read of the curve is the diagnostic.