Anita M. Rivera-Brown

Principles of Exercise Physiology: Responses to Acute Exercise and Long-term Adaptations to Training

Physical activity and fitness are associated with a lower prevalence of chronic diseases, such as heart disease, cancer, high blood pressure, and diabetes. This review discusses the bodys response to an acute bout of exercise and long‐term physiological adaptations to exercise training with an emphasis on endurance exercise. An overview is provided of skeletal muscle actions, muscle fiber types, and the major metabolic pathways involved in energy production. The importance of adequate fluid intake during exercise sessions to prevent impairments induced by dehydration on endurance exercise, muscular power, and strength is discussed. Physiological adaptations that result from regular exercise training such as increases in cardiorespiratory capacity and strength are mentioned. The review emphasizes the cardiovascular and metabolic adaptations that lead to improvements in maximal oxygen capacity.

Self-Reported Physical Activity in Hispanic Adults Living With HIV: Comparison With Accelerometer and Pedometer

Limited information is available regarding physical activity (PA) and its assessment in Hispanics living with HIV. This study compared self‐reported PA using the International Physical Activity Questionnaire (IPAQ) with objectively measured PA using the ActiGraph accelerometer and DigiWalker pedometer in 58 Hispanic adults with HIV. IPAQ was administered before and after a 7‐day period in which subjects wore the ActiGraph and DigiWalker. PA classification was based on ≥ 150 min/wk (IPAQ, ActiGraph) and ≥ 10,000 steps/day (DigiWalker). IPAQ‐PA was higher than ActiGraph‐PA (423 ± 298 vs. 165 ± 134 min/wk, respectively) (p < .01). There was a mismatch in PA classification with the IPAQ, ActiGraph, and DigiWalker (active = 81%, 54%, and 17%, respectively). Hispanics with HIV highly overestimated self‐reported PA. Nurse scientists and other investigators must consider accelerometers or pedometers to assess PA in this population.

Effect of Drink Pattern and Solar Radiation on Thermoregulation and Fluid Balance During Exercise in Chronically Heat Acclimatized Children

The purposes of this study were to examine the thermoregulatory and body fluid balance responses in chronically heat acclimatized children, i.e., indigenous to a tropical climate, during exercise in four outdoor conditions and the effects of dehydration on their thermoregulatory response. Nine children (age = 13.3 ± 1.9 yr, VO2max = 45.5 ± 9.2 ml · kg−1 · min−1) cycled at 60% VO2max each under four conditions: sun exposure voluntary drinking (SuVD), sun exposure forced drinking (SuFD), shaded voluntary drinking (ShVD), and shaded forced drinking (ShFD). Exercise sessions consisted of four 20‐min exercise bouts alternating with 25‐min rest periods. Globe temperature and the WBGT index were higher during SuVD and SuFD compared to ShVD and ShFD (P < 0.05). The change in rectal temperature, metabolic heat production, and heat storage did not differ among the conditions. Total water intake (% IBW) was higher during SuFD (4.1 ± 0.01) and ShFD (3.7 ± 0.1) compared to SuVD (2.1 ± 0.1) and ShVD (1.0 ± 0.1) and during SuVD compared to ShVD (P < 0.05). Sweating rate (L · hr−1) was higher during SuFD (0.7 ± 0.1) and ShFD (0.6 ± 0.1) compared to SuVD (0.5 ± 0.1) and ShVD (0.4 ± 0.1) (P < 0.05). Total fluid loss did not differ among conditions (SuVD = 1.7 ± 0.4; SuFD = 1.5 ± 0.4; ShVD = 2.1 ± 0.2; ShFD = 1.3 ± 0.3). Results indicate that when exercising in a tropical climate, chronically heat acclimatized children demonstrate mild voluntary dehydration and adequate heat dissipation.

Voluntary Intake of Sports Drinks and Water in Males and Females Running in Hot Environment: 1864

This is the complete report of a study presented in abstract form at the American College of Sports Medicine Annual Meeting in 2007. Medicine & Science in Sports & Exercise: May 2007 Volume 39 Issue 5 p S315. doi: 10.1249/01.mss.0000274223.49529.eb. The study was carried out at the University of Puerto Rico during LFA’s forced leave of absence from the University of Costa Rica, between 2005 and 2007. Sponsored by the Gatorade Sports Science Institute.