Dark chocolate (DC) is high in flavonoids and has been shown to increase nitric oxide in the blood. Increased nitric oxide has the potential to improve delivery of oxygen to muscle, especially in hypoxic conditions, such as altitude. Our aim was to assess the impact of DC supplementation on cycling performance at altitude. Twelve healthy, trained cyclists (n = 2 females, n = 10 males; age = 35  years; height = 177  cm; mass = 75.2 [11.0] kg; VO2max = 55  ml·kg−1·min−1) were randomized to supplement with 60 g of DC or placebo twice per day for 14 days in a double-blind crossover study. After the 2 weeks of supplementation, the participants attended a laboratory session in which they consumed 120 g of DC or placebo and then cycled for 90 min at 50% peak power output, followed immediately by a 10-km time trial (TT) at simulated altitude (15% O2). The plasma concentration of blood glucose and lactate were measured before and at 15, 30, 60, and 90 min during the steady-state exercise and post TT, while muscular and prefrontal cortex oxygenation was measured continuously throughout exercise using near-infrared spectroscopy. DC resulted in a higher concentration of blood glucose (5.5 [0.5] vs. 5.3 [0.9] mmol/L) throughout the trial and lower blood lactate concentration following the TT (7.7 [1.92] vs. 10.0 [4.6] mmol/L) compared with the placebo. DC had no effect on the TT performance (19.04 [2.16] vs. 19.21 ± 1.96 min) or oxygenation status in either the prefrontal cortex or muscle. The authors conclude that, although it provided some metabolic benefit, DC is not effective as an ergogenic aid during TT cycling at simulated altitude.
Effect of Dark Chocolate Supplementation on Tissue Oxygenation, Metabolism, and Performance in Trained Cyclists at Altitude
Keely Shaw, Jyotpal Singh, Luke Sirant, J. Patrick Neary, and Philip D. Chilibeck
Stretching is Superior to Brisk Walking for Reducing Blood Pressure in People With High–Normal Blood Pressure or Stage I Hypertension
Jongbum Ko, Dalton Deprez, Keely Shaw, Jane Alcorn, Thomas Hadjistavropoulos, Corey Tomczak, Heather Foulds, and Philip D. Chilibeck
Background: Aerobic exercise is recommended for reducing blood pressure; however, recent studies indicate that stretching may also be effective. The authors compared 8 weeks of stretching versus walking exercise in men and women with high–normal blood pressure or stage 1 hypertension (ie, 130/85–159/99 mm Hg). Methods: Forty men and women (61.6 y) were randomized to a stretching or brisk walking exercise program (30 min/d, 5 d/wk for 8 wk). Blood pressure was assessed during sitting and supine positions and for 24 hours using a portable monitor before and after the training programs. Results: The stretching program elicited greater reductions than the walking program (P < .05) for sitting systolic (146  to 140  vs 139  to 142  mm Hg), supine diastolic (85  to 78  vs 81  to 82  mm Hg), and nighttime diastolic (67  to 65  vs 68  to 73  mm Hg) blood pressures. The stretching program elicited greater reductions than the walking program (P < .05) for mean arterial pressure assessed in sitting (108  to 103  vs 105  vs 105  mm Hg), supine (102  to 96  vs 99  to 99  mm Hg), and at night (86  to 83  vs 88  to 93  mm Hg). Conclusions: An 8-week stretching program was superior to brisk walking for reducing blood pressure in individuals with high–normal blood pressure or stage 1 hypertension.