A brief review is provided on the relationship of strength to muscle cross-sectional area (CSA). It is commonly believed that maximal force and CSA are strongly related. Studies examining varying levels of training status display discordant data suggesting complex relationships between training status, CSA and peak force. It has been reported that trained participants had a significantly larger force to CSA ratio (F/CSA) than untrained males and females. Therefore, it is difficult to attribute all force changes due to training to CSA changes. In general, studies of CSA and strength suggest that sex differences may exist. For example, recreationally trained female weightlifters produced higher F/CSA than males at lower velocities of contraction. Definitive conclusions regarding sex differences, force production and CSA are difficult because of limited studies and equivocal results among these studies. Some studies have also examined the impact of aging on F/CSA. These studies seem to follow the same pattern as studies on sex differences and training status, with data suggesting that F/CSA varies unpredictably across ages and that differences may be attributed to factors other than age alone. In the papers reviewed, the relationship between force and CSA is neither consistent nor simple. Although some of the discrepancies between studies could be attributed to methodological variations, this does not seem likely to explain all differences. The F/CSA relationship seems complex, and future studies are required to elucidate the relationships among key factors in the expression of strength.

Ice hockey performance was studied during 10 contests to assess time-motion characteristics and associated physiological changes that occur for each position. Depending on the position played, the actual playing time per game for forwards and defensemen ranged between 20.7 and 28.0 min. The number of shifts ranged from 14 to 21 with an average playing time of 85.4 s/shift. Further analysis of each shift indicated that there was an average of 2.3 play stoppages which averaged 27.1 s, producing a continuous playing time of 39.7 s. Telemetered recordings of heart rate during each shift revealed sustained rates of between 170 and 174 beats/min over the three periods of the game. For both the forwards and defensemen, values for blood lactates were highest during the first and second periods (x = 78.0 and 66.1 mg/100 ml), then declined considerably during the third period (x = 44.5 mg/100 ml). Blood glucose showed a similar tendency (x = 139.3, 133.7, 114.1 mg/100 ml), while hematocrit and total protein showed little tendency to change.

Sweat lactate results from eccrine gland metabolism, however, the possible clearance of blood lactate through sweat has not been resolved. On separate days in an environmental chamber (32 +/- 1 C) 12 subjects completed a constant load (CON) (30 min at 40% VO2 max) and an interval cycling trial (INT) (15 one-min intervals at 80% VO2 max, each separated by one min rest) each designed to elicit different blood lactate responses. Each 30 min cycling trial was preceded by 15 min warm-up (30 watts) and followed by 15 min passive rest. Sweat and blood were analyzed for lactate concentration at 15, 25, 35, 45, and 60 min during CON and INT. Total body water loss was used to calculate sweat rate (ml/hr). Blood lactate was significantly greater (p < or = 0.05) at 25, 35, 45, and 60 min during INT compared to CON (approximately 5 mmol/L vs 1.5 mmol/L). Sweat lactate was not significantly different (p>0.05) between trials at any time (approximately 10 mmol/L). Sweat rates (approximately 600ml/hr) and estimated total lactate secretion were not significantly different (CON vs. INT) (p > 0.05). Elevated blood lactate was not associated with changes in sweat lactate concentration. Sweat lactate seems to originate in eccrine glands independent of blood lactate.

Context:The behaviors and beliefs of recreational runners with regard to hydration maintenance are not well elucidated.Objective: To examine which beverages runners choose to drink and why, negative performance and health experiences related to dehydration, and methods used to assess hydration status.Design: Cross-sectional study. Setting: Marathon registration site. Patients or Other Participants: Men (n = 146) and women (n = 130) (age = 38.3 ± 11.3 years) registered for the 2010 Little Rock Half-Marathon or Full Marathon. Intervention(s):A 23-item questionnaire was administered to runners when they picked up their race timing chips.Main Outcome Measure(s): Runners were separated into tertiles (Low, Mod, High) based on z scores derived from training volume, expected performance, and running experience. We used a 100-mm visual analog scale with anchors of 0 (never) and 100 (always). Total sample responses and comparisons between tertile groups for questionnaire items are presented. Results:The High group (58±31) reported greater consumption of sport beverages in exercise environments than the Low (42 ± 35 mm) and Mod (39 ± 32 mm) groups (P < .05) and perceived sport beverages to be superior to water in meeting hydration needs (P < .05) and improving performance during runs greater than 1 hour (P < .05). Seventy percent of runners experienced 1 or more incidents in which they believed dehydration resulted in a major performance decrement, and 45% perceived dehydration to have resulted in adverse health effects. Twenty percent of runners reported monitoring their hydration status. Urine color was the method most often reported (7%), whereas only 2% reported measuring changes in body weight.Conclusions: Greater attention should be paid to informing runners of valid techniques to monitor hydration status and developing an appropriate individualized hydration strategy.Key Words: dehydration, sport beverages, hydration monitoring Key Points• Most runners had experienced performance decrements that they attributed to dehydration. Almost half the runners had sustained heat-related illness symptoms that they related to dehydration.• Despite these adverse events, few participants monitored their hydration levels or used specific hydration plans.• Better dissemination of accurate scientific information about appropriate hydration practices may increase runners' safety.

To maximize training quality, athletes have sought nutritional supplements that optimize recovery. This study compared chocolate milk (CHOC) with a carbohydrate replacement beverage (CRB) as a recovery aid after intense exercise, regarding performance and muscle damage markers in trained cyclists. Ten regional-level cyclists and triathletes (maximal oxygen uptake 55.2 +/- 7.2 mL.kg(-1).min(-1)) completed a high-intensity intermittent exercise protocol, then 15-18 h later performed a performance trial at 85% of maximal oxygen uptake to exhaustion. Participants consumed 1.0 g carbohydrate.kg-1.h-1 of a randomly assigned isocaloric beverage (CHOC or CRB) after the first high-intensity intermittent exercise session. The same protocol was repeated 1 week later with the other beverage. A 1-way repeated measures analysis of variance revealed no significant difference (p = 0.91) between trials for time to exhaustion at 85% of maximal oxygen uptake (CHOC 13 +/- 10.2 min, CRB 13.5 +/- 8.9 min). The change in creatine kinase (CK) was significantly (p < 0.05) greater in the CRB trial than in the CHOC trial (increase CHOC 27.9 +/- 134.8 U.L(-1), CRB 211.9 +/- 192.5 U.L(-1)), with differences not significant for CK levels before the second exercise session (CHOC 394.8 +/- 166.1 U.L(-1), CRB 489.1 +/- 264.4 U.L(-1)) between the 2 trials. These findings indicate no difference between CHOC and this commercial beverage as potential recovery aids for cyclists between intense workouts.