1.
High-Intensity Single-Leg Cycling Improves Cardiovascular Disease Risk Factor Profile.
Gordon, N, Abbiss, CR, Maiorana, AJ, James, AP, Clark, K, Marston, KJ, Peiffer, JJ
Medicine and science in sports and exercise. 2019;(11):2234-2242
Abstract
INTRODUCTION Regular exercise can reduce the risk of developing cardiovascular disease through risk factor modification, with high-intensity exercise and more recently small muscle mass training providing alternatives to moderate-intensity exercise. METHODS This study randomly assigned 53 healthy middle-age adults (age, 62 ± 6 yr) to complete 24 sessions (8 wk; 3 d·wk) of exercise training, using either high-intensity double-leg cycling (n = 17; HITDL), high-intensity single-leg cycling (n = 18; HITSL), or moderate-intensity double-leg cycling (n = 18; MCTDL). Biomarkers of cardiovascular risk (total cholesterol, triglycerides, HDL-c, LDL-c, apo-B48, and glucose), anthropometry measures (body mass, body mass index, waist circumference, and waist-to-hip ratio), resting blood pressure, and aerobic capacity were assessed pre- and postintervention. RESULTS Total work completed was greater (P < 0.01) in MCTDL (5938 ± 1462 kJ) compared with the HITDL (3462 ± 1063 kJ) and HITSL (4423 ± 1875 kJ). Pre- to posttraining differences were observed for waist-to-hip ratio (0.84 ± 0.09 vs 0.83 ± 0.09; P < 0.01), resting systolic blood pressure (129 ± 11 vs 124 ± 12 mm Hg; P < 0.01), total cholesterol (5.87 ± 1.17 vs 5.55 ± 0.98 mmol·L; P < 0.01), and LDL-c (3.70 ± 1.04 vs 3.44 ± 0.84 mmol·L; P < 0.01), with no differences between conditions. In addition, aerobic capacity increased after training (22.3 ± 6.4 vs 24.9 ± 7.6 mL·kg·min; P < 0.01), with no differences between conditions. CONCLUSION These findings suggest that all three modes of exercise can be prescribed to achieve cardiovascular risk reduction in an aging population.
2.
Carbohydrate loading failed to improve 100-km cycling performance in a placebo-controlled trial.
Burke, LM, Hawley, JA, Schabort, EJ, St Clair Gibson, A, Mujika, I, Noakes, TD
Journal of applied physiology (Bethesda, Md. : 1985). 2000;(4):1284-90
Abstract
We evaluated the effect of carbohydrate (CHO) loading on cycling performance that was designed to be similar to the demands of competitive road racing. Seven well-trained cyclists performed two 100-km time trials (TTs) on separate occasions, 3 days after either a CHO-loading (9 g CHO. kg body mass(-1). day(-1)) or placebo-controlled moderate-CHO diet (6 g CHO. kg body mass(-1). day(-1)). A CHO breakfast (2 g CHO/kg body mass) was consumed 2 h before each TT, and a CHO drink (1 g CHO. kg(.)body mass(-1). h(-1)) was consumed during the TTs to optimize CHO availability. The 100-km TT was interspersed with four 4-km and five 1-km sprints. CHO loading significantly increased muscle glycogen concentrations (572 +/- 107 vs. 485 +/- 128 mmol/kg dry wt for CHO loading and placebo, respectively; P < 0.05). Total muscle glycogen utilization did not differ between trials, nor did time to complete the TTs (147.5 +/- 10.0 and 149.1 +/- 11.0 min; P = 0.4) or the mean power output during the TTs (259 +/- 40 and 253 +/- 40 W, P = 0.4). This placebo-controlled study shows that CHO loading did not improve performance of a 100-km cycling TT during which CHO was consumed. By preventing any fall in blood glucose concentration, CHO ingestion during exercise may offset any detrimental effects on performance of lower preexercise muscle and liver glycogen concentrations. Alternatively, part of the reported benefit of CHO loading on subsequent athletic performance could have resulted from a placebo effect.