The effects of lower body passive heating combined with mixed-method cooling during half-time on second-half intermittent sprint performance in the heat.

PURPOSE: This study examined the effects of combined cooling and lower body heat maintenance during half-time on second-half intermittent sprint performances. METHODS: In a repeated measures design, nine males completed four intermittent cycling trials (32.1 ± 0.3 °C and 55.3 ± 3.7% relative humidity), with either one of the following half-time recovery interventions; mixed-method cooling (ice vest, ice slushy and hand cooling; COOL), lower body passive heating (HEAT), combined HEAT and COOL (COMB) and control (CON). Peak and mean power output (PPO and MPO), rectal (Tre), estimated muscle (Tes-Mus) and skin (TSK) temperatures were monitored throughout exercise. RESULTS: During half-time, the decrease in Tre was substantially greater in COOL and COMB compared with CON and HEAT, whereas declines in Tes-Mus within HEAT and COMB were substantially attenuated compared with CON and COOL. The decrease in TSK was most pronounced in COOL compared with CON, HEAT and COMB. During second-half, COMB and HEAT resulted in a larger decrease in PPO and MPO during the initial stages of the second-half when compared to CON. In addition, COOL resulted in an attenuated decrease in PPO and MPO compared to COMB in the latter stages of second-half. CONCLUSION: The maintenance of Tes-Mus following half-time was detrimental to prolonged intermittent sprint performance in the heat, even when used together with cooling.

The effect of prior walking on coronary heart disease risk markers in South Asian and European men.

PURPOSE: Heart disease risk is elevated in South Asians possibly due to impaired postprandial metabolism. Running has been shown to induce greater reductions in postprandial lipaemia in South Asian than European men, but the effect of walking in South Asians is unknown. METHODS: Fifteen South Asian and 14 white European men aged 19-30 years completed two, 2-day trials in a randomised crossover design. On day 1, participants rested (control) or walked for 60 min at approximately 50 % maximum oxygen uptake (exercise). On day 2, participants rested and consumed two high-fat meals over a 9-h period during which 14 venous blood samples were collected. RESULTS: South Asians exhibited higher postprandial triacylglycerol [geometric mean (95 % confidence interval) 2.29 (1.82 to 2.89) vs. 1.54 (1.21 to 1.96) mmol L(-1) h(-1)], glucose [5.49 (5.21 to 5.79) vs. 5.05 (4.78 to 5.33) mmol L(-1) h(-1)], insulin [32.9 (25.7 to 42.1) vs. 18.3 (14.2 to 23.7) µU mL(-1) h(-1)] and interleukin-6 [2.44 (1.61 to 3.67) vs. 1.04 (0.68 to 1.59) pg mL(-1) h(-1)] than Europeans (all ES ≥ 0.72, P ≤ 0.03). Between-group differences in triacylglycerol, glucose and insulin were not significant after controlling for age and percentage body fat. Walking reduced postprandial triacylglycerol [1.79 (1.52 to 2.12) vs. 1.97 (1.67 to 2.33) mmol L(-1) h(-1)] and insulin [21.0 (17.0 to 26.0) vs. 28.7 (23.2 to 35.4) µU mL(-1) h(-1)] (all ES ≥ 0.23. P ≤ 0.01), but group differences were not significant. CONCLUSIONS: Healthy South Asians exhibited impaired postprandial metabolism compared with white Europeans, but these differences were diminished after controlling for potential confounders. The small-moderate reduction in postprandial triacylglycerol and insulin after brisk walking was not different between the ethnicities.

Exercise and coronary heart disease risk markers in South Asian and European men.

PURPOSE: South Asians have a higher-than-average risk of CHD. The reasons for this are unclear, but physical inactivity and/or poor responsiveness to exercise may play a role. This study compared the effect of prior exercise on postprandial triacylglycerol (TAG), glucose, insulin, interleukin-6, and soluble intercellular adhesion molecule-1 concentrations in South Asian and European men. METHODS: Ten healthy South Asian men (i.e., nine Indian men and one Pakistani man) and 10 healthy European men age 20 to 28 yr completed two 2-d trials (exercise and control) in a randomized crossover design. On the afternoon of day 1 of the exercise trial, participants ran on a treadmill for 60 min at approximately 70% of maximal oxygen uptake. Participants rested on day 1 of the control trial. On day 2 of both trials, participants rested and consumed high-fat (57% of energy content) test meals for breakfast (0 h) and lunch (4 h). Fourteen venous blood samples were collected from a cannula between 0 and 9 h for metabolic measurements. RESULTS: Three-way ANOVA identified higher (P < 0.05) postprandial TAG and insulin concentrations in South Asian versus European men. Exercise lowered postprandial TAG and interleukin-6 and elevated soluble intercellular adhesion molecule-1 concentrations. An interaction effect indicated a greater decrease (22% vs 10%) in TAG area under the concentration versus time curve after exercise in South Asian than in European men. CONCLUSIONS: Postprandial TAG and insulin responses to high-fat meals were elevated in these South Asian men, but acute exercise was equally, if not more, effective for reducing postprandial lipemia in South Asian than in European men.