Exercise tolerance in a hot and humid climate in heat-acclimatized girls and women.

This study compared physiological responses associated with exercise tolerance in girls (G) and women (W) of similar fitness and heat acclimatization level during exercise in a hot and humid outdoor environment (33.4 degrees C and 55.1 % RH; WBGT = 29.9 +/- 0.2 degrees C). Nine pre-menarcheal G (age = 11.3 yr) and nine W (age = 26.8 yr), matched for aerobic capacity and heat acclimatization level, performed a cycling session at 60 % VO2max until fatigue. A sports drink was provided periodically to prevent dehydration. Tolerance time was not different between the groups (G = 56.9 +/- 6.3, W = 76.5 +/- 9.9 min, p > 0.05). During exercise, sweat rate (G = 9.1 +/- 1.1, W = 12.0 +/- 1.1 ml.m(-2).min(-1)), the increase in rectal temperature [T(re)] (G = 0.9 +/- 0.1, W = 1.1 +/- 0.1 degrees C), and heat storage (G = 10.6 +/- 5.3, W = 20.5 +/- 4.5 W.m(-2)) did not differ between the groups. At fatigue, T(re) (G = 38.2 +/- 0.1, W = 38.4 +/- 0.1 degrees C), heart rate (G = 167.3 +/- 7.3, W = 171 +/- 3.3 beats.min(-1)), stroke index (G = 48.3 +/- 1.5, W = 52.4 +/- 1.8 ml.m(-2)), and forearm skin blood flow (G = 9.5 +/- 1.3, W = 11.7 +/- 1.5 ml.100 ml(- 1).min(-1)) did not differ between the groups. Similar to women, the main reasons reported by girls to stop exercising in the heat were localized leg fatigue and gluteus muscle discomfort. We conclude that heat-acclimatized girls exhibit an adequate cardiovascular and thermoregulatory adjustment while exercising in a hot and humid outdoor environment when hypohydration is prevented.

Anaerobic power and achievement of VO2 plateau in pre-pubertal boys.

A low anaerobic power has been proposed as a factor that may be limiting the achievement of a plateau in VO2 of children who perform maximal aerobic power tests. This study examined the frequency of plateau achievement in pre-pubertal children and compared VO2max, peak (PP) and mean (MP) anaerobic power in subjects who either achieved a plateau (PLAT) or did not (NO PLAT). Eighteen healthy pre-pubertal (Tanner Stage, pubic hair = 1) males (age = 9.1 1.6 yrs, ht = 134.4 +/- 9.7cm, wt = 33.3 +/- 9.2kg, VO2max = 40.0 +/- 6.7 ml x kg(-1) min(-1)) were tested. All subjects completed a 30 sec Wingate Anaerobic Test and a McMaster aerobic protocol to volitional fatigue on a cycle ergometer. Only 33% of the subjects met the PLAT criterion. No differences were found for PP or MP between those who achieved a plateau and those who did not (PLAT: PP= 6.3 +/- 0.8W/kg and MP = 5.2 +/- 0.7W/kg; NO PLAT: PP= 6.3 +/- 1.2 W/kg and MP = 5.2 +/- 1.3 W/kg). We conclude that anaerobic power is not a factor limiting the achievement of a plateau in VO2 of pre-pubertal boys who perform maximal aerobic power tests.

Drink composition, voluntary drinking, and fluid balance in exercising, trained, heat-acclimatized boys.

This study examined the effects of beverage composition on the voluntary drinking pattern, body fluid balance, and thermoregulation of heat-acclimatized trained boys exercising intermittently in outdoor conditions (wet bulb globe temperature 30.4 +/- 1.0 degreesC). Twelve boys (age 13.4 +/- 0.4 yr) performed two 3-h sessions, each consisting of four 20-min cycling bouts at 60% maximal aerobic power alternating with 25-min rest. One of two beverages was assigned: unflavored water (W) or flavored water plus 6% carbohydrate and 18 mmol/l Na (CNa). Drinking was ad libitum. Total intake was higher (P < 0.05) during CNa (1,943 +/- 190 g) compared with W (1,470 +/- 143 g). Euhydration was maintained with CNa (+0.18% body wt), but a mild dehydration resulted with W (-0.94% body wt; P < 0.05). Sweat loss, much higher than previously published for children of similar age, was similar between conditions (CNa = 1,644.7 +/- 117.5; W = 1,750.2 +/- 152.7 g). The increase in rectal temperature (CNa = 0.86 +/- 0.3; W = 0.76 +/- 0.1 degreesC), heart rate, and all perceptual variables did not differ between conditions. In conclusion, a flavored carbohydrate-electrolyte drink prevents voluntary dehydration in trained heat-acclimatized boys exercising in a tropical climate despite their large sweat losses. Because hydration changes were minor, the thermoregulatory strain observed was similar between conditions.

[Anthropometric and physiologic profile of Puerto Rican athletes: female softball]. / Perfil antropométrico y fisiológico de atletas puertorriqueños: softbol femenino.

This study was conducted to describe and compare various anthropometric, body composition, cardiorespiratory, metabolic and neuromuscular characteristics of 12 female athletes, members of the Puerto Rico national softball team. The subjects were divided into three categories according to their game specific requirements (game position): infielders (n = 5), outfielders (n = 4), and pitchers (n = 3). The mean and standard deviations of all the variables in each group was calculated. These athletes demonstrated high levels of body fat and below optimal levels of flexibility, cardiorespiratory endurance, and muscular strength and endurance. The results revealed deficiencies in the health related fitness components and in the physical preparation for sports competition. These results also suggest that the subjects are at risk for the development of cardiovascular diseases, sport injuries, and poor sport performance.

[Morbidity during the XVI Central American and Caribbean Games: Puerto Rican delegation, Mexico 1990]. / Morbilidad durante los XVI Juegos Deportivos Centroamericanos y del Caribe: Delegación de Puerto Rico, México 1990.

The health services offered to the Puerto Rican Delegation during the XVI Central American and Caribbean Sports Games in México in 1990 included: medical, dental and psychological assistance, physical therapy and services on the playing field. From the consultation sheets completed during the Games we obtained information about the use of these services. The 336 members of the Puerto Rico Delegation in the village at México City had 1,838 encounters with the health team. Of these, 991 were medical consults, 55 group therapies, 466 physical therapy sessions and 326 encounters in the sports venues. Among the encounters for medical evaluation the most frequent problems were athletic injuries (318; 32.1%), respiratory problems (240; 24.2%), gastrointestinal conditions (126; 12.7%) and dental services (119; 12.0%). The most frequent athletic injuries were first degree strains (83; 26.1%), tendinitis (56; 17.6%), contusions (42; 13.2%), myositis (40; 12.6%) and first degree sprains (28; 8.8%). The health problems found were diversed and in the majority of cases mild in character, which can be attend by adequately trained on sports health primary health professionals.

[Female physiology during exercise]. / Fisiología de la mujer durante el ejercicio.

Physiological responses and adaptations of women to exercise are influenced by her genetically determined morphological and functional characteristics, and by her level of physical fitness. Physiological responses of women during submaximal and maximal exercise differ quantitatively from those of men but adaptations to training are qualitatively similar in both. Studies demonstrate that differences between the sexes in performance of athletic events that require high aerobic or anaerobic capacity are due, to a large extent, to differences in body structure and composition: the average woman is smaller and lighter and has less muscle mass than the average man. These characteristics influence physiologic responses of the musculoskeletal, cardiovascular and respiratory systems during exercise. This article describes physiological responses of women during exercise in relation to her sex related morphological characteristics, and the adaptations that occur with physical training.