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Purpose: This study aimed 1) to examine the accuracy with which W′ reconstitution (W′REC) is estimated by the W′ balance (W′BAL) models after a 3-min all-out cycling test (3MT), 2) to determine the effects of a 3MT on the power–duration relationship, and 3) to assess whether accounting for changes in the power–duration relationship during exercise improved estimates of W′REC. Methods: The power–duration relationship and the actual and estimated W′REC were determined for 12 data sets extracted from our laboratory database where participants had completed two 3MT separated by 1-min recovery (i.e., control [C-3MT] and fatigued [F-3MT]). Results: Actual W′REC (6.3 ± 1.4 kJ) was significantly overestimated by the W′BAL·ODE (9.8 ± 1.3 kJ; P < 0.001) and the W′BAL·MORTON (16.9 ± 2.6 kJ; P < 0.001) models but was not significantly different to the estimate provided by the W′BAL·INT (7.5 ± 1.5 kJ; P > 0.05) model. End power (EP) was 7% lower in the F-3MT (263 ± 40 W) compared with the C-3MT (282 ± 44 W; P < 0.001), and work done above EP (WEP) was 61% lower in the F-3MT (6.3 ± 1.4 kJ) compared with the C-3MT (16.9 ± 3.2 kJ). The size of the error in the estimated W′REC was correlated with the reduction in WEP for the W′BAL·INT and W′BAL·ODE models (both r > −0.74, P < 0.01) but not the W′BAL·MORTON model (r = −0.18, P > 0.05). Accounting for the changes in the power–duration relationship improved the accuracy of the W′BAL·ODE and W′BAL·MORTON, but they remained significantly different to actual W′REC. Conclusions: These findings demonstrate that the power–duration relationship is altered after a 3MT, and accounting for these changes improves the accuracy of the W′BAL·ODE and the W′BAL·MORTON, but not W′BAL·INT models. These results have important implications for the design and use of mathematical models describing the energetics of exercise performance. [ABSTRACT FROM AUTHOR]

Purpose: We tested the hypotheses that a highly cushioned running shoe (HCS) would 1) improve incremental exercise performance and reduce the oxygen cost (Oc) of submaximal running, and 2) attenuate the deterioration in Oc elicited by muscle damage consequent to a downhill run. Methods: Thirty-two recreationally active participants completed an incremental treadmill test in an HCS and a control running shoe (CON) for the determination of Oc and maximal performance. Subsequently, participants were pair matched and randomly assigned to one of the two footwear conditions to perform a moderate-intensity running bout before and 48 h after a 30-min downhill run designed to elicit muscle damage. Results: Incremental treadmill test performance was improved (+5.7%; +1:16 min:ss; P < 0.01) in the HCS when assessed in the nondamaged state, relative to CON. This coincided with a significantly lower Oc (−3.2%; −6 mL·kg−1·km−1; P < 0.001) at a range of running speeds and an increase in the speed corresponding to 3 mM blood lactate (+3.2%; +0.4 km·h−1; P < 0.05). As anticipated, the downhill run resulted in significant changes in biochemical, histological, and perceptual markers of muscle damage, and a significant increase in Oc (+5.2%; 10.1 mL·kg−1·km−1) was observed 48 h post. In the presence of muscle damage, Oc was significantly lower in HCS (−4.6%; −10 mL·kg−1·km−1) compared with CON. Conclusions: These results indicate that HCS improved incremental exercise performance and Oc in the absence of muscle damage and show, for the first time, that despite worsening of Oc consequent to muscle damage, improved Oc in HCS is maintained. [ABSTRACT FROM AUTHOR]

The influence of anthropometry and body composition on running economy is unclear, with previous investigations involving small relatively homogeneous groups of runners and limited anthropometric/composition measurements. Purpose: To comprehensively investigate the relationships of anthropometry and body composition with running economy within a large heterogeneous sample of runners. Methods: Eighty-five runners (males [M], n = 45; females [F], n = 40), of diverse competitive standard, performed a discontinuous protocol of incremental treadmill running (4-min stages, 1 km·h−1 increments) to establish locomotory energy cost (LEc) of running at submaximal speeds (averaged across 10–12 km·h−1; the highest common speed < lactate turnpoint). Measurements of anthropometry, including segment lengths, perimeters, masses and moments of inertia, and body composition were obtained using tape-based measurements and dual-energy x-ray absorptiometry. Results: Absolute LEc (ABSLEc, kcal·km−1) was positively correlated with 21 (of 27) absolute anthropometric variables in both male and female cohorts. Multiple-regression analyses revealed that one variable (mean perimeter z score) explained 49.4% (M) and 68.9% (F) of the variance in ABSLEc. Relative LEc (RELLEc, kcal·kg−1·km−1) was also correlated with five (M) and seven (F) normalized anthropometric variables, and regression analyses explained 31.6% (M; percentage bone mass and normalized hip perimeter) and 33.3% (F, normalized forearm perimeter) of the variance in RELLEc. Conclusions: These findings provide novel and robust evidence that anthropometry and body composition variables, predominantly indicative of relative slenderness, explain a considerable proportion of the variance in running economy (i.e., more slender, lower energy cost). We, therefore, recommend that runners and coaches are attentive to relative slenderness in selecting and training athletes with the aim of enhancing running economy, and improving distance running performance. [ABSTRACT FROM AUTHOR]