The aims of the study were to investigate whether starting cadence had an effect on 10-s sprint-performance indices in friction-loaded cycle ergometry and to investigate the influence of method of power determination. In a counterbalanced order, 12 men and 12 women performed three 10-s sprints using a stationary (0 rev/min), moderate (60 rev/min), and high (120 rev/min) starting cadence Calculated performance indices were peak power, cadence at peak power, time to peak power, and work to peak power. When the uncorrected method of power determination was applied, there was a main effect for starting cadence in female participants for peak power (stationary 635 ± 183.7 W, moderate 615.4 ± 168.9 W and high 798.4 ± 120.1 W) and cadence at peak power (89.8 ± 2.3 rev/min, 87.9 ± 21.5 rev/min, and 113.1 ± 12.5 rev/min). For both the uncorrected and directly measured methods of power determination in men and women, there was a main effect for starting cadence for time to peak power and work to peak power. In women, for an uncorrected method of power determination, it can be concluded that starting cadence does affect peak power and cadence at peak power. This effect is, however, negated by a direct-measurement method of power determination. In men and women, for both uncorrected and directly measured methods o power determination, time to peak power and work to peak power were affected by starting cadence. Therefore, a higher-cadence start is unsuitable, particularly when sprint-performance indices are determined from an uncorrected method.
Rachel L. Wright, Dan M. Wood and David V.B. James
David V.B. James, Linda J. Reynolds and Sara Maldonado-Martin
Heart rate variability (HRV) has been promoted as a noninvasive method of evaluating autonomic influence on cardiac rhythm. Although female subjects predominate in the walking studies, no study to date has examined the influence of the duration of a moderate intensity walking physical activity bout on HRV in this population.
Twelve healthy physically active middle-aged women undertook 2 conditions; 20min (W20) and 60min (W60) bouts of walking on a treadmill. Resting HRV measures were obtained before (−1 h), and 1 h and 24 h after the walking bouts.
Mean NN interval (ie, normal-to-normal intervals between adjacent QRS complexes) was significantly lower (P = .017) at +1 h in W60 (832, 686−979ms) compared with W20 (889, 732−1046ms). A borderline main effect for time was observed for both the SDNN intervals in W60 (P = .056), and for low frequency (LFabs) power in W60 (P = .047), with post hoc tests revealing a significant increase between −1 h (51, 33−69 ms and 847, 461−1556 ms2) and +1 h (65, 34−97ms and 1316, 569−3042 ms2) for SDNN and LFabs power, respectively, but no increase at +24h compared with −1 h.
It appears that a walking bout of 60 min duration does alter cardiac autonomic influence in healthy active women, and this alteration is not evident after 20 min of walking. Given the rather subtle effect, further studies with larger sample sizes are required to explore the nature of the changes in cardiac autonomic influence following a prolonged bout of walking.
Stephen B. Draper, Dan M. Wood, Jo Corbett, David V.B. James and Christopher R. Potter
We tested the hypothesis that prior heavy-intensity exercise reduces the difference between asymptotic oxygen uptake (VO2) and maximum oxygen uptake (VO2max) during exhaustive severe-intensity running lasting ≍2 minutes. Ten trained runners each performed 2 ramp tests to determine peak VO2 (VO2peak) and speed at venti-latory threshold. They performed exhaustive square-wave runs lasting ≍2 minutes, preceded by either 6 minutes of moderate-intensity running and 6 minutes rest (SEVMOD) or 6 minutes of heavy-intensity running and 6 minutes rest (SEVHEAVY). Two transitions were completed in each condition. VO2 was determined breath by breath and averaged across the 2 repeats of each test; for the square-wave test, the averaged VO2 response was then modeled using a monoexponential function. The amplitude of the VO2 response to severe-intensity running was not different in the 2 conditions (SEVMOD vs SEVHEAVY; 3925 ± 442 vs 3997 ± 430 mL/min, P = .237), nor was the speed of the response (τ; 9.2 ± 2.1 vs 10.0 ± 2.1 seconds, P = .177). VO2peak from the square-wave tests was below that achieved in the ramp tests (91.0% ± 3.2% and 92.0% ± 3.9% VO2peak, P < .001). There was no difference in time to exhaustion between conditions (110.2 ± 9.7 vs 111.0 ± 15.2 seconds, P = .813). The results show that the primary VO2 response is unaffected by prior heavy exercise in running performed at intensities at which exhaustion will occur before a slow component emerges.
David V.B. James, Leigh E. Sandals, Stephen B. Draper, Sara Maldonado-Martín and Dan M. Wood
Previously it has been observed that, in well-trained 800-m athletes, VO2max is not attained during middle-distance running events on a treadmill, even when a race-type pacing strategy is adopted. Therefore, the authors investigated whether specialization in a particular running distance (400-m or 800-m) influences the VO2 attained during running on a treadmill.
Six 400-m and six 800-m running specialists participated in the study. A 400-m trial and a progressive test to determine VO2max were completed in a counterbalanced order. Oxygen uptakes attained during the 400-m trial were compared to examine the influence of specialist event.
A VO2 plateau was observed in all participants for the progressive test, demonstrating the attainment of VO2max. The VO2max values were 56.2 ± 4.7 and 69.3 ± 4.5 mL · kg−1 · min−1 for the 400-m- and 800-m-event specialists, respectively (P = .0003). Durations for the 400-m trial were 55.1 ± 4.2 s and 55.8 ± 2.3 s for the 400-m- and 800-m-event specialists, respectively. The VO2 responses achieved were 93.1% ± 2.0% and 85.7% ± 3.0% VO2max for the 400-m- and 800-m-event specialists, respectively (P = .001).
These results demonstrate that specialist running events do appear to influence the percentage of VO2max achieved in the 400-m trial, with the 800-m specialists attaining a lower percentage of VO2max than the 400-m specialists. The 400-m specialists appear to compensate for a lower VO2max by attaining a higher percentage VO2max during a 400-m trial.
Heidi L. Meehan, Stephen J. Bull, Dan M. Wood and David V.B. James
The present study explored the experiences of five competitive endurance athletes (1 female, 4 male) diagnosed with the overtraining syndrome (OTS). A multicontextual method of inquiry was used, which first involved a medical examination whereby OTS was diagnosed according to established criteria. In addition, 2 questionnaires were administered: the Athlete Daily Hassle Scale (Albinson & Pearce, 1998) and the Coping Response Inventory (Moos, 1992), and a semistructured interview was conducted. Individual case studies were then developed and cross-case analysis carried out. Findings from the present study illustrate that together with sport stress, nonsport stress appears to make an important contribution to the experience of those athletes diagnosed with the OTS. This finding provides evidence to support anecdotes in previous reports.
Martin J. Turner, Marc V. Jones, David Sheffield, Matthew J. Slater, Jamie B. Barker and James J. Bell
This study assessed whether cardiovascular (CV) reactivity patterns indexing challenge and threat states predicted batting performance in elite male county (N = 12) and national (N = 30) academy cricketers. Participants completed a batting test under pressure, before which CV reactivity was recorded in response to ego-threatening audio instructions. Self-reported self-efficacy, control, achievement goals, and emotions were also assessed. Challenge CV reactivity predicted superior performance in the Batting Test, compared with threat CV reactivity. The relationships between self-report measures and CV reactivity, and self-report measures and performance were inconsistent. A small subsample of participants who exhibited threat CV reactivity, but performed well, reported greater self-efficacy than participants who exhibited threat CV reactivity, but performed poorly. Also a small subsample of participants who exhibited challenge reactivity, but performed poorly, had higher avoidance goals than participants with challenge reactivity who performed well. The mechanisms for the observed relationship between CV reactivity and performance are discussed alongside implications for future research and applied practice.