Effect of Stroke Rate Manipulation on Oxygen Uptake in Constant Speed Swimming Scott McLean, Ph.D.

Collaborators Southwestern University, Georgetown, TX, USA Jimmy Smith, Ph.D. Graham Ice Institute for Exercise and Environmental Medicine, Dallas, TX, USA Dean Palmer, M.S. Robert Wiskera, B.A. Institute for Fundamental and Clinical Human Movement Sciences, Amsterdam, Netherlands. Martin Truijens, Ph.D.

Optimization of human movement Gait –Choose SR/SL that minimizes O 2 uptake Cycling –Choose higher cadence than most economical –Minimize muscle stress? longer step shorter step faster cadence slower cadence Cavanagh & Williams (1982) Marsh & Martin (1993) Running Cycling

SR and Oxygen Uptake Swaine and Reilly (1983) swim bench Pawelczyk et al. (1991) –swim in ~1.0 m/s –Manipulated SR –HR& –Combination of SL and SR to minimize metabolic cost –Smaller effect than in running Pawelczyk et al. (1991) Intensity? –8 min swims –Blood lactates 6-7 mmol Stroke Rate Control? –Metronome –CV 5-7%

Purpose To examine the manipulation of stroke rate on oxygen uptake in submaximal, constant speed swimming It was hypothesized that deviations from the preferred stroke rate (SR) would increase oxygen uptake when swimming at a constant submaximal speed.

Measures Stroke Rate –controlled using a Finis  Tempo Trainer –monitored with time needed to complete 10 strokes. Oxygen Uptake –Monitored on breath-by-breath system to identify steady state –Measured using Douglas bag technique Heart Rate –Polar™ HR monitor Kick Rate –computed using the time needed to complete 30 kicks determined from underwater video RPE

Methods Nine competitive swimmers –33.3±13.6 yrs –175.3±8.6 cm –74.9±12.2 kg Swim in flume at 1.0 m/s

Accommodation Heart Rate monitor applied 5-min warm-up swim in a flume at 1.0 m/s Headgear and mouthpiece fitted to subject 5 minute swim at 1.0 m/s –participant accommodated to equipment –determine preferred SR

Protocol –Randomized order –Each trial continued for 1-min after steady state was verified (~4-5 min) VO2, HR, and KR measured during the final min of each trial RPE was reported immediately after each trial. -20% -10% +10% +20% Preferred SR

Steady State

Oxygen Uptake * *

Heart Rate * *

RPE * *

Kick Rate * *

Summary These data suggest that these swimmers preferred to swim at the slowest SR (or the longest stroke length) that did not require an increase in KR and thus an increase in VO2.

Now Where? SR x S relationship Training to increase SL Changes in SR/SL during the season or phases of the season

Grimston and Hay, 1985 “long-limbed individuals with large hands and feet have a predisposition to success in swimming” ParameterSLSR Axilla XSA0.74 * * Arm Length0.68 * * Hand XSA0.57 * Leg Length * Foot XSA0.68 * *p<0.05

 S depended on ΔSR and ΔSL (Craig and Pendergast, 1976) Representative Data McLean et al., 2003

SL tends to decrease through a race (Letzelter and Freitag, 1982; Hay et al., 1983) SL negatively correlated with S (r=-0.59, p<0.05) but not SR (r=0.08) (Hay et al.,1983) 200 free

WHY SR and SL? Easy to measure Useful during training and competition

Stroke Length (SL) Stroke Rate (SR) What do we know?

Stroke Length (SL) Stroke Rate (SR) Anthropometrics

Stroke Length (SL) Stroke Rate (SR) Anthropometrics Changes with speed

Stroke Length (SL) Stroke Rate (SR) Anthropometrics Changes during race Changes with speed

Stroke Length (SL) Stroke Rate (SR) Anthropometrics Changes during race Differences b/w strokes Changes with speed

What’s missing from these studies? Physiological cost Relationship of SR, SL, S and metabolic cost? Limited ability to describe this relationship –Need ability to control stroke characteristics –Flume

Effect of Stroke Rate Manipulation on Oxygen Uptake in Constant Speed Swimming Scott McLean, Ph.D.1, Dean Palmer, M.S 2, Graham Ice 1, Robert Wiskera, B.A 2, Martin Truijens, Ph.D. 3, and Jimmy Smith, Ph.D Southwestern University, Georgetown, TX, USA 2 Institute for Exercise and Environmental Medicine, Dallas, TX, USA 3 Institute for Fundamental and Clinical Human Movement Sciences, Amsterdam, Netherlands.