Effects of practice and preferred rate on perceived exertion, metabolic variables and movement control

One interesting feature of motor skill learning and control is our propensity to reduce the metabolic energy cost of achieving the task goal with practice and, if unconstrained, to adapt movements to task constraints using an energy-efficient preferred mode. This study investigated the effects of preferred rate and practice on metabolic variables, ratings of perceived exertion (RPE) and movement control. Six healthy well-trained male volunteers with no experience of rowing undertook one session per day over 6 days on a Concept II rowing ergometer at a power output of 100 W at preferred stroke rate (PR) and then at experimenter imposed rates of +20% (PR+) and -20% (PR-) of preferred. Heart rate and RPE declined significantly over days and there was an associated but nonsignificant reduction in oxygen consumption. Heart rate, oxygen consumption and RPE were significantly lower when rowing at preferred rate and economy was significantly greater. There was a trend toward reduced variability in the rowing cycle duration over practice days but the effect was not significant. Cycle duration was significantly less variable in the PR- phase than in the PR and PR+ phases, the latter phases were equally variable. Overall the data provide support for the view that motor learning is associated with changes to movement control parameters that reflect increased economy of energy expenditure in achieving the task goal. In addition, preferred modes (here preferred rate) appear to be associated with more economical but not more stable performances than non-preferred.