摘要:

BAKER, J., E. BROWN, G. HILL, G. PHILLIPS, R. WILLIAMS, and B. DAVIES. Handgrip contribution to lactate production and leg power during high-intensity exercise.Med. Sci. Sports Exerc., Vol. 34, No. 6, pp. 1037–1040, 2002.PurposeThe purpose of this study was to examine the upper-body contribution via handgrip to power profiles and blood lactate concentrations during high-intensity cycle ergometry.MethodsNine trained male subjects each completed a 20-s high-intensity cycle ergometer test twice, in a random manner, using two protocols, with a handgrip (WG), and without handgrip (WOHG). Capillary (earlobe) blood samples were obtained pre- and post-exercise. Blood samples were corrected for plasma volume changes and analyzed to determine blood lactate concentrations.ResultsIn the WG protocol, mean (±SEM) blood lactate concentrations sampled over the three conditions were 0.98 ± 0.33 mmol·L−1, 5.68 ± 0.46 mmol·L−1, and 9.14 ± 0.38 mmol·L−1, respectively. During the WOHG protocol, blood lactate values recorded were 0.99 ± 0.26 mmol·L−1, 5.58 ± 0.58 mmol·L−1, and 7.62 ± 0.65 mmol·L−1, respectively. Differences were found (P< 0.05) from rest to 4 min after exercise for both groups. Differences in concentrations were also observed between groups at the 4-min postexercise blood-sampling stage. Peak power output values recorded using the WG protocol were also greater (1461 ± 94 W vs 1136 ± 88 W;P< 0.05). No differences were recorded for mean power output (MPO), fatigue index (FI), or work done (WD).ConclusionResults indicate significant differences in power output and blood lactate concentrations between protocols. These findings suggest that the performance of traditional style leg-cycle ergometry requires a muscular contribution from the whole body. As such, researchers should consider this, both in terms of the allocation of ergometer loads, and in the analysis of blood-borne metabolites.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

D. BISHOP, D. BONETTI, and B. DAWSON. The influence of pacing strategy on &OV0312;O2and supramaximal kayak performance.Med. Sci. Sports Exerc., Vol. 34, No. 6, pp. 1041–1047, 2002.PurposeThe purpose of this study was to investigate the effects of manipulating pacing strategy on &OV0312;O2and kayak ergometer performance in well-trained paddlers.MethodsEight well-trained kayak paddlers (500-m time = 115-125 s) first performed a graded exercise test for determination of &OV0312;O2maxand lactate (La−) parameters. On subsequent days and in a random, counterbalanced order, subjects performed a 2-min, kayak ergometer test using either an all-out start or even pacing strategy.ResultsThere was a significantly greater peak power (747.6 ± 152.0 vs 558.3 ± 110.1 W) and average power (348.5 ± 47.6 vs 335.5 ± 44.8 W) using the all-out start strategy, when compared with the even-paced strategy. There was however, no significant difference between the two pacing strategies for peak &OV0312;O2, accumulated oxygen deficit (AOD), peak [La−], or posttest pH. Using the all-out start, total &OV0312;O2was significantly greater (7.3 ± 0.8 vs 6.9 ± 0.8 L).ConclusionThe results of this study indicate that 2-min kayak ergometer performance is significantly greater following an all-out start strategy when compared with an even-paced strategy. The improved performance appears to be attributable to faster &OV0312;O2kinetics, without a significant change in the total AOD (although the AOD distribution was altered).

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

RUBY, B. C., T. C. SHRIVER, T. W. ZDERIC, B. J. SHARKEY, C. BURKS, and S. TYSK. Total energy expenditure during arduous wildfire suppression.Med. Sci. Sports Exerc., Vol. 34, No. 6, pp. 1048–1054, 2002.PurposeThe purpose of this investigation was to determine the total energy expenditure (TEE) by using the doubly labeled water (DLW) methodology during 5 d of wildfire suppression in Montana, California, Florida, Washington, and Idaho.MethodsSeventeen wildland firefighters (from three Interagency Hot Shot crews,N= 8 men, height = 177 ± 7 cm, weight = 74.6 ± 6.4 kg, age = 24.5 ± 1.8 yr;N= 9 women, height = 170 ± 7 cm, weight = 65.2 ± 8.0 kg, age = 25.0 ± 1.3 yr) served as subjects. Before wildland fire suppression, each subject was given an oral dose of2H2O and H218O (approximately 0.23 g2H2O·kg estimated TBW−1and 0.39 g H218O·kg estimated TBW−1). Urine samples were collected between 0400 and 0600 daily. TEE was calculated using the two-point method for days 1–3 and 1–5, with the TEE for days 4–5 calculated by extrapolation. Urine samples from other crew members not participating in the DLW protocol were collected at the same times and used to adjust calculations of isotopic elimination for background shifts.ResultsTEE was 17.4 ± 3.7 and 17.5 ± 6.9 MJ·d−1during days 1–3 and 4–5, respectively. The energy expenditure associated with physical activity (EEA) was 8.8 ± 3.0 and 8.9 ± 6.1 MJ·d−1for days 1–3 and 4–5, respectively.ConclusionThe current data demonstrate consistently high daily energy expenditure in the wildland firefighter. These data also demonstrate that the doubly labeled water methodology is an appropriate methodology for the measure of TEE during unpredictable field operations if adjustments are made for changes in background enrichment and elevated water turnover.

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0195-9131    

出版商:OVID    

年代:2002

数据来源: OVID