In the current study we investigated changes in voluntary rhythmic leg movement frequency (freely chosen cycling cadence) and rhythmic movement pattern (tangential pedal force profile) after fatiguing hip flexion and hip extension exercises. Nine healthy individuals performed ergometer cycling at freely chosen cadence and at a cadence of 1 Hz before and after fatiguing hip flexion and hip extension exercises. The freely chosen cadence was not affected after fatiguing exercises. An alteration of key characteristics of the tangential pedal force profile was found during cycling at a cadence of 1 Hz after hip flexion exercise. Thus, minimum tangential pedal force decreased by 12.0 ± 11.3% (p = .006), while maximum tangential pedal force increased by 4.6 ± 4.2% (p = .011), and the phase with negative tangential pedal force increased by 2.6 ± 3.2% (p = .040). In conclusion, novel information was obtained on aspects of rhythmic leg movement behavior in form of pedaling after fatiguing exercise.
Ernst A. Hansen, Michael Voigt, Uwe G. Kersting and Pascal Madeleine
Mark Holten Mora-Jensen, Pascal Madeleine and Ernst Albin Hansen
The present study analyzed (a) whether a recently reported phenomenon of repeated bout rate enhancement in finger tapping (i.e., a cumulating increase in freely chosen finger tapping frequency following submaximal muscle activation in the form of externally unloaded voluntary tapping) could be replicated and (b) the hypotheses that the faster tapping was accompanied by changed vertical displacement of the fingertip and changed peak force during tapping. Right-handed, healthy, and recreationally active individuals (n = 24) performed two 3-min index finger tapping bouts at freely chosen tapping frequency, separated by 10-min rest. The recently reported phenomenon of repeated bout rate enhancement was replicated. The faster tapping (8.8 ± 18.7 taps/min, corresponding to 6.0 ± 11.0%, p = .033) was accompanied by reduced vertical displacement (1.6 ± 2.9 mm, corresponding to 6.3 ± 14.9%, p = .012) of the fingertip. Concurrently, peak force was unchanged. The present study points at separate control mechanisms governing kinematics and kinetics during finger tapping.
Geoffrey L. Hartley and Stephen S. Cheung
The present study investigated relationships between changes in power output (PO) to torque (TOR) or freely chosen cadence (FCC) during thermal loading. Twenty participants cycled at a constant rating of perceived exertion while ambient temperature (Ta) was covertly manipulated at 20-min intervals of 20 °C, 35 °C, and 20 °C. The magnitude responses of PO, FCC and TOR were analyzed using repeated-measures ANOVA, while the temporal correlations were analyzed using Auto-Regressive Integrated Moving Averages (ARIMA). Increases in Ta caused significant thermal strain (p < .01), and subsequently, a decrease in PO and TOR magnitude (p < .01), whereas FCC remained unchanged (p = .51). ARIMA indicates that changes in PO were highly correlated to TOR (stationary r 2 = .954, p = .04), while FCC was moderately correlated (stationary r2 = .717, p = .01) to PO. In conclusion, changes in PO are caused by a modulation in TOR, whereas FCC remains unchanged and therefore, unaffected by thermal stressors.