Some reports suggest variation in physiological responses and athletic performance, for female athletes at specific phases of the menstrual cycle. However, inconsistent findings are common due to the inappropriate verification of menstrual cycle phase, small subject numbers, high intra- and interindividual variability in estrogen and progesterone concentration, and the pulsatile secretion of these hormones. Therefore, the oral contraceptive (OC) cycle may provide a more stable environment in which to evaluate the acute effect of reproductive hormones on physiological variables and exercise performance. To date, most of the OC research has compared differences between OC use and nonuse, and few researchers have examined within-cycle effects of the OC. It is also apparent that OC use is becoming far more prevalent in athletes; hence the effect of the different exogenous and endogenous hormonal profiles on athletic performance should be investigated. Research to date identifies potential for variation in aerobic performance, anaerobic capacity, anaerobic power and reactive strength throughout an OC cycle. The purpose of this review is to present and evaluate the current literature on the physiology of exercise and athletic performance during the OC cycle.
Claire Rechichi, Brian Dawson and Carmel Goodman
Jennifer K. Ormerod, Tabatha A. Elliott, Timothy P. Scheett, Jaci L. VanHeest, Lawrence E. Armstrong and Carl M. Maresh
The purposes of this study were to characterize measures of fluid intake and perception of thirst in women over a 6-week period of exercise-heat acclimation and outdoor training and examine if this lengthy acclimation period would result in changes in fluid intake that differ from those previously reported in men utilizing a shorter acclimation protocol of 8–10 days. Voluntary water intake (11–17 °C) and perception of thirst were measured in a group of 5 women (21–26 yr) undergoing exercise-heat acclimation for 90 min/day, 3 days/wk (36 °C, rh 50–70%) and outdoor training 3 days/wk for 6 weeks. Decreased drinking during acclimation was characterized by a decrease in the number of drinks (35 ± 10 to 17 ± 5; p < .05), greater time to first drink (9.9 ± 2.0 to 23.1 ± 4.7 min; p < .05), and a decrease in total volume ingested per week (3310 ± 810 to 1849 ± 446 ml; p < .05) through the 6-week study. Mean perceived thirst measurements remained low and showed only slight variance (3 ± 0.4 to 5 ± 0.4). These observations support a psycho-physiological response pattern different than that previously observed during 8–10 day acclimation protocols in men.
Andrew C. Morris, Ira Jacobs, Tom M. McLellan, Abbey Klugerman, Lawrence C.H. Wang and Jiri Zamecnik
The purpose of this study was to examine the effects of ginseng extract ingestion on physiological responses to intense exercise. Subjects performed a control ride (CN) on a cycle ergometer, followed by placebo (PL) and ginseng (GS) treatments. Ginseng was ingested as 8 or 16 mg/kg body weight daily for 7 days prior to trial GS. Venous blood was sampled for FFA, lactate, and glucose analyses. Due to similar findings for both dose groups, the subjects were considered as one group. Lactate, FFA,
Mindy Millard-Stafford, Linda B. Rosskopf, Teresa K. Snow and Bryan T. Hinson
Twelve highly trained male runners ran 15 km at self-selected pace on a treadmill in warm conditions to demonstrate differences in physiological responses, fluid preferences, and performance when ingesting sports drinks or plain water before and during exercise. One hour prior to the start of running, an equal volume (1,000 ml) of either water or a 6% or an 8% carbohydrate-electrolyte (CE) drink was ingested. Blood glucose was significantly higher 30 min following ingestion of 6% and 8% CE compared to water, significantly lower at 60 min postingestion with both sports drinks than with water, but similar after 7.5 km of the run for all beverages. During the first 13.4 km, oxygen uptake and run times were not different between trials; however, the final 1.6-km performance run was faster with both CE drinks compared to water. Despite a lower preexercise blood glucose, CE consumption prior to and during exercise significantly improved performance in the last 1.6 km of a 15-km run compared to water.
Charles J. Hardy, Evelyn G. Hall and Perry H. Prestholdt
Two experiments are reported that investigate the mediational role of social influence in the self-perception of exertion. In Experiment 1, subjects performed three 15-min trials on a cycle ergometer at 25%, 50%, and 75% VO2max, both in the presence of another performer (a coactor) and alone. The results indicated that subjects reported lower RPEs when performing with another, particularly at the moderate (50%) intensity. In Experiment 2, subjects performed one 15-min trial at 50% of VO2max, both alone and in the presence of another performer (coactor) exhibiting nonverbal "cues" that the work was either extremely easy or extremely difficult. The results indicated that subjects exposed to the low-intensity cue information reported lower RPEs than when performing alone. Mo significant differences were noted for those subjects exposed to the high-intensity cue information. These findings are discussed in terms of a self-presentational analysis. That such effects were evidenced without physiological responses (VO2, VE, HR) accompanying them supports the notion that psychological variables can play a significant role in the self-perception of exertion. These results, however, are limited to untrained individuals exercising at moderate intensities.
Hervé Assadi and Romuald Lepers
To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session.
Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined.
Maximal physiological parameters were similar during the 45-15FIT and TR tests (VO2max 58.6 ± 5.9 mL · kg−1 · min−1 for TR vs 58.5 ± 7.0 mL · kg−1 · min−1 for 45-15FIT; HRmax 200 ± 8 beats/min for TR vs 201 ± 7 beats/min for 45-15FIT). MAV45-15 was significantly (P < .001) greater than MAVTR (17.7 ± 1.1 vs 15.6 ± 1.4 km/h). t90% and t95% VO2max during the 30-s/30-s performed at MAVTR were significantly (P < .01) lower than during the 30-s/30-s performed at MAV45-15. Similar VO2 during intermittent tests performed at MAV45-15 and at MAVTR can be obtained by reducing the recovery time or using active recovery.
The results suggested that the 45-15FIT is an accurate field test to determine VO2max and that MAV45-15 can be used during high-intensity intermittent training such as 30-s runs interspersed with 30-s rests (30-s/30-s) to elicit a high percentage of VO2max.
Thomas W. Buford, Douglas B. Smith, Matthew S. O’Brien, Aric J. Warren and Stephen J. Rossi
The purpose of the present investigation was to examine the physiological response of collegiate wrestlers to their competitive season.
Eleven Division I collegiate wrestlers (mean ± SD; 19.45 ± 1.13 y) volunteered and completed 4 testing sessions throughout the course of the collegiate wrestling season. Testing sessions were conducted pre-, mid-, and postseason, as well as before the national tournament. Testing consisted of weigh-in, skinfold body composition testing, and a 50-rep concentric, isokinetic leg extension muscle endurance test (180°/s). Muscular performance variables measured included peak torque, peak torque at fatigue, percent decline, and peak torque/body mass ratio.
A significant increase (P < .05) of 2.9% was observed for body mass between midseason and postseason (2.38 kg). From pre- to postseason, a mean increase of 3.8% (3.1 kg) was observed for body mass. An increase (P < .05) in BF% of 2.9% was observed between prenationals and postseason. No significant differences (P > .05) were observed between consecutive time points for quadriceps peak torque; however, there was a significant increase (P < .05) between preseason and prenationals (23.39 N·m). Peak torque at fatigue was greater (P < .05) at midseason than preseason, representing an increase of 9.82 N·m. Between midseason and prenationals testing, we observed an 11% increase (P < .05) in %DCLN. Finally, we noted an increase (P < .05) from 0.6 to 0.69 in peak torque/body mass ratio between preseason and prenationals.
Our results indicate that while force values seem to suffer at midseason, the wrestlers compensated and were strongest just before their national competition.
Thomas I. Gee, Duncan N. French, Karl C. Gibbon and Kevin G. Thompson
This study investigated the pacing strategy adopted and the consistency of performance and related physiological parameters across three 2000-m rowing-ergometer tests.
Fourteen male well-trained rowers took part in the study. Each participant performed three 2000-m rowing-ergometer tests interspersed by 3–7 d. Throughout the trials, respiratory exchange and heart rate were recorded and power output and stroke rate were analyzed over each 500 m of the test. At the completion of the trial, assessments of blood lactate and rating of perceived exertion were measured.
Ergometer performance was unchanged across the 3 trials; however, pacing strategy changed from trial 1, which featured a higher starting power output and more progressive decrease in power, to trials 2 and 3, which were characterized by a more conservative start and an end spurt with increased power output during the final 500 m. Mean typical error (TE; %) across the three 2000-m trials was 2.4%, and variability was low to moderate for all assessed physiological variables (TE range = 1.4−5.1%) with the exception of peak lactate (TE = 11.5%).
Performance and physiological responses during 2000-m rowing ergometry were found to be consistent over 3 trials. The variations observed in pacing strategy between trial 1 and trials 2 and 3 suggest that a habituation trial is required before an intervention study and that participants move from a positive to a reverse-J-shaped strategy, which may partly explain conflicting reports in the pacing strategy exhibited during 2000-m rowing-ergometer trials.
Matt B. Brearley and James P. Finn
Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.
To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.
Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.
Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.
Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.
Jocelyn K. Mara, Kevin G. Thompson and Kate L. Pumpa
To investigate the physical and physiological response to different formats of various-sided games.
Eighteen elite women’s soccer players wore 15-Hz global positioning system devices and heart-rate (HR) monitors during various-sided games (small, 4 vs 4 and 5 vs 5; medium, 6 vs 6 and 7 vs 7; large, 8 vs 8 and 9 vs 9).
Players covered more relative sprinting distance during large-sided games than in small-sided (P < .001, d = 0.69) and medium-sided (P < .001, d = 0.54) games. In addition, a greater proportion of total acceleration efforts that had a commencement velocity <1 m/s were observed in small-sided games (44.7% ± 5.5%) than in large-sided games (36.7% ± 10.6%) (P = .018, d = 0.94). This was accompanied by a greater proportion of acceleration efforts with a final velocity equivalent to the sprint threshold in large-sided games (15.4% ± 7.7%) than in small-sided games (5.2% ± 2.5%) (P < .001, d = 1.78). The proportion of time spent in HR zone 4 (>85% maximum HR) was greater during small-sided games (69.8% ± 2.5%) than in medium- (62.1% ± 2.8%, d = 2.90) and large-sided games (54.9% ± 3.1%) (P < .001, d = 5.29).
The results from this study demonstrate that coaches can use small-sided games as an aerobic conditioning stimulus and to develop players’ explosiveness and repeat-sprint ability over short durations. Large-sided games can be used to maintain aerobic capacity and develop maximum speed over longer distances.