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BACKGROUND: The glycemic index (GI) of a food is thought to directly reflect the rate of digestion and entry of glucose into the systemic circulation. The blood glucose concentration, however, represents a balance of both the entry and the removal of glucose into and from the blood, respectively. Such direct quantification of the postprandial glucose curve with respect to interpreting the GI is lacking in the literature. OBJECTIVE: We compared the plasma glucose kinetics of low- and high-GI breakfast cereals. DESIGN: On 2 occasions, plasma insulin concentrations and plasma glucose kinetics (by constant-rate infusion of [6,6-(2)H(2)]glucose) were measured in 6 healthy males for 180 min after they fasted overnight and then consumed an amount of corn flakes (CF) or bran cereal (BC) containing 50 g available carbohydrate. RESULTS: The GI of CF was more than twice that of BC (131.5 +/- 33.0 compared with 54.5 +/- 7.2; P < 0.05), despite no significant differences in the rate of appearance of glucose into the plasma during the 180-min period. Postprandial hyperinsulinemia occurred earlier with BC than with CF, resulting in a 76% higher plasma insulin concentration at 20 min (20.4 +/- 4.5 compared with 11.6 +/- 2.1 micro U/mL; P < 0.05). This was associated with a 31% higher rate of disappearance of glucose with BC than with CF during the 30-60-min period (28.7 +/- 3.1 compared with 21.9 +/- 3.1 micro mol x kg(-)(1) x min(-)(1); P < 0.05). CONCLUSION: The lower GI of BC than of CF was not due to a lower rate of appearance of glucose but instead to an earlier postprandial hyperinsulinemia and an earlier increase in the rate of disappearance of glucose, which attenuated the increase in the plasma glucose concentration. Copyright © 2003 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]

Physical inactivity is the fourth leading cause of death in the world. It is associated with myriad diseases and premature death. Two possible contributing factors are postprandial lipidaemia (PPL), which accelerates atherosclerosis, and impaired whole-body fat oxidation, which contributes to obesity. Acute exercise in physically active people is effective for increasing whole body fat oxidation and lowering PPL the next morning. However, in people who have low physical activity (<8000 steps/day), an acute bout of exercise (1 h at 62% maximal oxygen consumption) has no effect on increasing fat oxidation or reducing PPL ('exercise resistance'). The acute harms of inactivity are not due to the lack of exercise and are more powerful than the benefits of exercise, at least regarding fat metabolism. The increase in mortality with reduced daily steps is remarkably steep. Low background steps/day also impair the metabolic adaptations to short-term endurance training, suggesting that the ills of inactivity extend beyond fat metabolism. 'Exercise resistance' with inactivity could be a culprit, causing atherosclerosis, or maybe also a harbinger (impaired fat oxidation) of more widespread diseases. Recommendations regarding the amount of moderate to vigorous exercise needed for health should factor in the amount of background activity (i.e. ∼8000 steps/day) necessary to avoid 'exercise resistance'., (© 2024 The Authors. The Journal of Physiology © 2024 The Physiological Society.)

Integrative cardiovascular responses to heat stress during endurance exercise depend on various variables, such as thermal stress and exercise intensity. This review addresses how increases in skin temperature alter and challenge the integrative cardiovascular system during upright submaximal endurance exercise, especially when skin is hot (i.e. >38°C). Current evidence suggests that exercise intensity plays a significant role in cardiovascular responses to hot skin during exercise. At rest and during mild intensity exercise, hot skin increases skin blood flow and abolishes cutaneous venous tone, which causes blood pooling in the skin while having little impact on stroke volume and thus cardiac output is increased with an increase in heart rate. When the heart rate is at relatively low levels, small increases in heart rate, skin blood flow, and cutaneous venous volume do not compromise stroke volume, so cardiac output can increase to fulfill the demands for maintaining blood pressure, heat dissipation, and the exercising muscle. On the contrary, during more intense exercise, hot skin does not abolish exercise-induced cutaneous venoconstriction possibly due to high sympathetic nerve activities; thus, it does not cause blood pooling in the skin. However, hot skin reduces stroke volume, which is associated with a decrease in ventricular filling time caused by an increase in heart rate. When the heart rate is high during moderate or intense exercise, even a slight reduction in ventricular filling time lowers stroke volume. Cardiac output is therefore not elevated when skin is hot during moderate intensity exercise., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 Informa UK Limited, trading as Taylor & Francis Group.)

The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O 2 max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, and SPORTDiscus were systematically searched on May 9, 2020, and updated on September 14, 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of "all-out" and non-"all-out" efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies were deemed eligible. The estimated SMDs based on the random-effects model were -0.56 (95% CI: -0.79, -0.33, p < 0.001) for V̇O 2 max, -0.43 (95% CI: -0.67, -0.20, p < 0.001) for aerobic performance, and -0.44 (95% CI: -0.70, -0.18, p < 0.001) for anaerobic performance after sSIT vs. no exercise/usual training. However, there were no significant differences (p > 0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g., cycling, running, paddling, and punching) to improve V̇O 2 max, aerobic, and anaerobic performances in physically active young healthy adults and athletes., (© 2022 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.)

Prolonged sitting prevents a 1-h bout of running from improving fat oxidation and reducing plasma triglycerides. This "exercise resistance" can be prevented by taking 8500 steps·d-1 or by interrupting 8 h of sitting with hourly cycle sprints. We hypothesize that there is an interplay between background physical activity (e.g., steps·d-1) and the exercise stimuli in regulating some acute and chronic adaptations to exercise., (Copyright © 2022 by the American College of Sports Medicine.)

Introduction: High-intensity interval training is an effective tool to improve cardiovascular fitness and maximal anaerobic power. Different methods of high-intensity interval training have been studied but the effects of repeated maximal effort cycling with very short exercise time (i.e., 4 s) and short recovery time (15-30 s) might suit individuals with limited time to exercise., Purpose: We examined the effects of training at near maximal anaerobic power during cycling (PC) on maximal anaerobic power, peak oxygen consumption (V˙O2peak), and total blood volume in 11 young healthy individuals (age: 21.3 ± 0.5 yr) (six men, five women)., Methods: Participants trained three times a week for 8 wk performing a PC program consisting of 30 bouts of 4 s at an all-out intensity (i.e., 2 min of exercise per session). The cardiovascular stress progressively increased over the weeks by decreasing the recovery time between sprints (30-24 s to 15 s), and thus, total session time decreased from 17 to <10 min., Results: Power cycling elicited a 13.2% increase in V˙O2peak (Pre: 2.86 ± 0.18 L·min-1, Post: 3.24 ± 0.21 L·min-1; P = 0.003) and a 7.6% increase in total blood volume (Pre: 5139 ± 199 mL, Post: 5529 ± 342 mL; P < 0.05). Concurrently, maximal anaerobic power increased by 17.2% (Pre: 860 ± 53 W, Post: 1,009 ± 71 W; P < 0.001)., Conclusions: A PC training program employing 30 bouts of 4 s duration for a total of 2 min of exercise, resulting in a total session time of less than 10 min in the last weeks, is effective for improving total blood volume, V˙O2peak and maximal anaerobic power in young healthy individuals over 8 wk. These observations require reconsideration of the minimal amount of exercise needed to significantly increase both maximal aerobic and anaerobic power., (Copyright © 2021 by the American College of Sports Medicine.)

Purpose: This study determined if the level of background physical inactivity (steps per day) influences the acute and short-term adaptations to intense aerobic training., Methods: Sixteen untrained participants (23.6 ± 1.7 yr) completed intense (80%-90% V˙O2peak) short-term training (5 bouts of exercise over 9 d) while taking either 4767 ± 377 steps per day (n = 8; low step) or 16,048 ± 725 steps per day (n = 8; high step). At baseline and after 1 d of acute exercise and then after the short-term training (posttraining), resting metabolic responses to a high-fat meal (i.e., plasma triglyceride concentration and fat oxidation) were assessed during a 6-h high-fat tolerance test. In addition, responses during submaximal exercise were recorded both before and after training during 15 min of cycling (~79% of pretraining V˙O2peak)., Results: High step displayed a reduced incremental area under the curve for postprandial plasma triglyceride concentrations by 31% after acute exercise and by 27% after short-term training compared with baseline (P < 0.05). This was accompanied by increased whole-body fat oxidation (24% and 19%; P < 0.05). Furthermore, stress during submaximal exercise as reflected by heart rate, blood lactate, and deoxygenated hemoglobin were all reduced in high step (P < 0.05), indicating classic training responses. Despite completing the same training regimen, low step showed no significant improvements in postprandial fat metabolism or any markers of stress during submaximal exercise after training (P > 0.05). However, the two groups showed a similar 7% increase in V˙O2peak (P < 0.05)., Conclusion: When completing an intense short-term exercise training program, decreasing daily background steps from 16,000 to approximately 5000 steps per day blunts some of the classic cardiometabolic adaptations to training. The blunting might be more pronounced regarding metabolic factors (i.e., fat oxidation and blood lactate concentration) compared with cardiovascular factors (i.e., V˙O2peak)., (Copyright © 2021 by the American College of Sports Medicine.)

Purpose: Interval exercise allows very high-power outputs to be maintained, a key for stimulating training adaptations. The main purpose of this study was to develop a sprint interval protocol that stimulated both anaerobic and aerobic systems while maximizing power output and minimizing fatigue. The secondary goal was to investigate the influence of inter-sprint recovery duration., Methods: Sixteen (8 females) participants (age: 23.5 ± 3.4 years, peak oxygen consumption (VO 2peak ): 45.6 ± 9.2 ml kg -1  min -1 ) took part in this study. The exercise protocol involved 30 bouts of 4 s maximal cycling sprints using an 'Inertial Load Ergometer'. Recovery durations between sprints of 15, 30 and 45 s were studied in three trials., Results: Peak power output (PPO) was maintained while taking 45 and 30 s of recovery, although it was 9% higher (p < 0.05) during 45 vs. 30 s. PPO with 15 s recovery declined 18% (p < 0.05) and then stabilized as did oxygen consumption (72±2% VO 2peak ) at a level that might reflect the peak rate of ATP-PC resynthesis from oxidative metabolism. The 15-, 30-, and 45 s trials elicited 72, 56, and 49% VO 2peak and 86, 80, and 75% of maximal heart rate (all p<0.001). Perceived exertion increased with shorter recovery periods but remained at 12.6-14.7 and never became 'very hard'., Conclusion: The present study describes the use of an inertial-load ergometer to accommodate repeated 4 s maximal cycling sprints that elicit 72% VO 2peak when the recovery period is 15 s. However, a recovery duration of 15 s was insufficient for the maintenance of power generation., Trial Registration Number and Date: NCT04448925, 26 Jun 2020; retrospectively registered to clinicaltrials.gov.

Purpose: Reductions in skeletal muscle mass, beginning after the third decade of life, reduce maximal neuromuscular power (Pmax). Maximal aerobic power generation is also reduced. The primary purpose of this study was to investigate the effectiveness of maximal power cycling (PC) training using an inertial load ergometer on skeletal muscle mass and cardiovascular function in untrained 50- to 68-yr-old participants., Methods: The study used a pre- or postoutcome exercise intervention testing untrained 50- to 68-yr-old adults (n = 39, M = 15, mean ± SE = 58.5 ± 0.8, range = 50-68 yr). Over the course of 8 wk, participants performed 15 min of training 3 times per week. Each session involved repeated (15-30 times) 4-s sprints of PC. Measurements were thigh muscle volume, total body lean mass, Pmax, peak oxygen consumption, cardio-ankle vascular index, performance on functional tests of living (FTLChair and FTLRamp), and intermuscular fat volume., Results: Training for 8 wk increased thigh muscle volume (3.7% ± 0.9%, P < 0.001) and total body lean mass (1.5% ± 0.4%, P < 0.01) while increasing total body mass (TBM) (1.4% ± 0.3%, P < 0.01). Physical performance measures increased significantly (all P < 0.05) with improvements in Pmax (12.0% ± 1.5%); peak oxygen consumption (9.8% ± 1.8%), and FTL (8.5% ± 1.3% to 17.2% ± 2%). Cardio-ankle vascular index was significantly decreased -2.3% ± 1.1% (P < 0.05), indicating reduced arterial stiffness., Conclusions: These results demonstrate that 8 wk of PC training at true maximal power was effective at increasing muscle mass and maximal power, as well as maximal cardiovascular capacity and functional tasks in untrained 50- to 68-yr-olds., (Copyright © 2020 by the American College of Sports Medicine.)

Introduction: Two benefits of acute exercise are the next day's lowering of the postprandial plasma triglyceride response to a high-fat meal and increased fat oxidation. However, if activity levels (daily steps) are very low, these acute adaptations to exercise do not occur. This phenomenon has been termed "exercise resistance." This study sought to systematically reduce daily step number and identify the range of step counts that elicit "exercise resistance.", Methods: Ten participants completed three, 5-d trials in a randomized, crossover design with differing levels of step reduction. After 2 d of controlled activity, participants completed 2 d of LOW, LIMITED, or NORMAL steps (2675 ± 314, 4759 ± 276, and 8481 ± 581 steps per day, respectively). Participants completed a 1-h bout of running on the evening of the second day. High-fat tolerance tests were performed on the next morning, and postprandial responses were compared., Results: After LOW and LIMITED, postprandial incremental area under the curve (AUC) of plasma triglyceride was elevated 22%-23% compared with NORMAL (P < 0.05). Whole body fat oxidation was also significantly lower (16%-19%, P < 0.05, respectively) in LOW and LIMITED compared with NORMAL. No significant differences were found between LOW and LIMITED., Conclusion: Two days of step reduction to approximately 2500-5000 steps per day in young healthy individuals impairs the ability of an acute bout of exercise to increase fat oxidation and attenuate postprandial increases in plasma triglycerides. This suggests that "exercise resistance" occurs in individuals taking approximately 5000 or fewer steps per day, whereas 8500 steps per day protects against exercise resistance in fat metabolism. It seems that fat metabolism is influenced more by the inhibitory effects of inactivity than by the stimulating effects derived from 1 h of moderate-intensity running., (Copyright © 2020 by the American College of Sports Medicine.)

Purpose: The biomechanical differences between cyclists with a high compared with a low blood lactate threshold (HLT; 80% VO 2max vs LLT, 70% VO 2max ) have yet to be completely described. We hypothesize that HLT cyclists reduce the stress placed on the knee extensor muscles by increasing the relative contribution from the hip joint during high-intensity cycling., Method: Sixteen well-trained endurance athletes, with equally high VO 2max while cycling and running completed submaximal tests during incremental exercise to identify lactate threshold ([Formula: see text]) while running and cycling. Subjects were separated into two groups based on % VO 2max at LT during cycling (high; HLT: 80.2 ± 2.1% VO 2max ; n = 8) and (LLT: 70.3 ± 2.9% VO 2max ; n = 8; p < 0.01). Absolute and relative joint specific powers were calculated from kinematic and pedal forces using inverse dynamics while cycling at intensities ranging from 60-90% VO 2max for between group comparisons., Result: There was no difference between HLT and LLT in [Formula: see text] (p > 0.05) while running. While cycling in LLT, knee joint absolute power increased with work rate (p < 0.05); however, in HLT no changes in knee joint absolute power occurred with increased work rate (p > 0.05). The HLT generated significantly greater relative hip power compared with the LLT group at 90% VO 2max (p < 0.05)., Conclusion: These data suggest that HLT cyclists exhibit a greater relative hip contribution to power output during cycling at 90% VO 2max . These observations support the theory that lactate production during cycling can be reduced by spreading the work rate between various muscle groups.

High postprandial plasma lipids (PPL; i.e., triglycerides) are a risk factor for cardiovascular disease. Physical inactivity, characterized by prolonged sitting and a low step count, elevates PPL and thus risk of disease., Purpose: This study determined if the interruption of prolonged sitting (i.e., 8 h of inactivity) with hourly cycling sprints of only 4-s duration each (i.e., 4 s × 5 per hour × 8 h = 160 s·d SPRINTS) improves PPL. The 4-s sprints used an inertial load ergometer and were followed by 45 s of seated rest., Methods: Four men and four women participated in two trials. Interventions consisted of an 8-h period of sitting (SIT), or a trial with equal sitting time interrupted with five SPRINTS every hour. The morning after the interventions, PPL and fat oxidation were measured over a 6-h period. Plasma glucose, insulin, and triglyceride concentrations were measured bihourly and incremental area under the curve (AUC) was calculated., Results: No differences (P > 0.05) between interventions were found for plasma insulin or glucose AUC. However, SPRINTS displayed a 31% (408 ± 119 vs 593 ± 88 mg·dL per 6 h; P = 0.009) decrease in plasma triglyceride incremental AUC and a 43% increase in whole-body fat oxidation (P = 0.001) when compared with SIT., Conclusions: These data indicate that hourly very short bouts (4 s) of maximal intensity cycle sprints interrupting prolonged sitting can significantly lower the next day's postprandial plasma triglyceride response and increase fat oxidation after a high-fat meal in healthy young adults. Given that these improvements were elicited from only 160 s of nonfatiguing exercise per day, it raises the question as to what is the least amount of exercise that can acutely improve fat metabolism and other aspects of health.

Prolonged periods of sedentary behavior are linked to cardiometabolic disease independent of exercise and physical activity. This study examined the effects of posture by comparing one day of sitting (14.4 ± 0.3 h) to one day of standing (12.2 ± 0.1 h) on postprandial metabolism the following day. Eighteen subjects (9 men, 9 women; 24 ± 1 y) completed two trials (sit or stand) in a crossover design. The day after prolonged sitting or standing the subjects completed a postprandial high fat/glucose tolerance test, during which blood and expired gas was collected immediately before and hourly for 6 h after the ingestion of the test meal. Indirect calorimetry was used to measure substrate oxidation while plasma samples were analyzed for triglyceride, glucose, and insulin concentrations. Standing resulted in a lower fasting plasma triglyceride concentration (p = 0.021) which was primarily responsible for an 11.3% reduction in total area under the curve (p = 0.022) compared to sitting. However, no difference between trials in incremental area under the curve for plasma triglycerides was detected (p>0.05). There were no differences in substrate oxidation, plasma glucose concentration, or plasma insulin concentration (all p>0.05). These data demonstrate that 12 h of standing compared to 14 h of sitting has a small effect the next day by lowering fasting plasma triglyceride concentration, and this contributed to a 11.3% reduction in postprandial plasma triglyceride total area under the curve (p = 0.022) compared to sitting., Competing Interests: The authors have declared that no competing interests exist.

To study effects of the gender-packaging of science, technology, engineering, and mathematics (STEM) toys, mother-child dyads (31 daughters; 30 sons; M = 5.2 years) were randomly assigned to play with a mechanical toy packaged for girls (GoldieBlox) or boys (BobbyBlox). When familiarizing themselves with the toy to prepare for play, mothers given BobbyBlox built more with toy pieces than did mothers given GoldieBlox. During dyadic play, mothers with sons built more; mothers with daughters read the toy's narrative instructions more. Children's independent play likewise varied with game packaging. Girls learned the mechanical belt-drive principle better from playing with BobbyBlox; boys learned the principle better from playing with GoldieBlox. Implications for gender-schema theories, STEM interventions, and toy marketing are discussed., (© 2018 Society for Research in Child Development.)

It is well known that hyperthermia lowers stroke volume (SV) during moderate-intensity prolonged exercise, yet the underlying mechanism is inconclusive, especially when skin temperature (Tsk) is hot (≥38°C)., Purpose: In the present study, HR was independently lowered by a low dose of β1-blockade (βB) to investigate its effect on SV during exercise when skin is hot. The effect of rapid skin cooling on reversing cardiovascular responses was also examined., Methods: Nine men cycled at 62% V˙O2peak wearing a water-perfused suit for 20 min during three conditions: (a) moderate Tsk (~33°C) (MOD), (b) hot Tsk (~38°C) (HOT), and (c) hot Tsk (38°C) with βB (HOT-βB). Skin temperature was then rapidly cooled at 20 min in all trials by cold water (0°C-2°C) perfusion while subjects continued cycling for another 20 min., Results: When HR was lowered during HOT-βB (152 ± 4 bpm) to the same level as MOD (150 ± 4 bpm; P = 0.30), SV in HOT-βB (132 ± 8 mL) was also restored to the same level as MOD (129 ± 7 mL, P = 0.37) even with a significantly higher cutaneous blood flow (CBF) and lower mean arterial blood pressure. When Tsk was rapidly cooled, cardiac output, HR, and CBF significantly decreased while SV remained lower in HOT. Forearm venous volume was not different between trials during heating and cooling., Conclusions: The increase in HR rather than an increase in CBF or forearm venous volume was responsible for the decrease in SV during moderate-intensity exercise when Tsk was held at 38°C.

John O. Holloszy, as perhaps the world's preeminent exercise biochemist/physiologist, published >400 papers over his 50+ year career, and they have been cited >41,000 times. In 1965 Holloszy showed for the first time that exercise training in rodents resulted in a doubling of skeletal muscle mitochondria, ushering in a very active era of skeletal muscle plasticity research. He subsequently went on to describe the consequences of and the mechanisms underlying these adaptations. Holloszy was first to show that muscle contractions increase muscle glucose transport independent of insulin, and he studied the mechanisms underlying this response throughout his career. He published important papers assessing the impact of training on glucose and insulin metabolism in healthy and diseased humans. Holloszy was at the forefront of rodent studies of caloric restriction and longevity in the 1980s, following these studies with important cross-sectional and longitudinal caloric restriction studies in humans. Holloszy was influential in the discipline of cardiovascular physiology, showing that older healthy and diseased populations could still elicit beneficial cardiovascular adaptations with exercise training. Holloszy and his group made important contributions to exercise physiology on the effects of training on numerous metabolic, hormonal, and cardiovascular adaptations. Holloszy's outstanding productivity was made possible by his mentoring of ~100 postdoctoral fellows and substantial NIH grant funding over his entire career. Many of these fellows have also played critical roles in the exercise physiology/biochemistry discipline. Thus it is clear that exercise biochemistry and physiology will be influenced by John Holloszy for numerous years to come.

Acute exercise improves postprandial lipemia, glucose tolerance, and insulin sensitivity, all of which are risk factors for cardiovascular disease. However, recent research suggests that prolonged sedentary behavior might abolish these healthy metabolic benefits. Accordingly, this study aimed to elucidate the impact of an acute bout of exercise on postprandial plasma triglyceride, glucose, and insulin concentrations after 4 days of prolonged sitting (~13.5 h/day). Ten untrained to recreationally active men ( n = 5) and women ( n = 5) completed a counterbalanced, crossover study. Four days of prolonged sitting without exercise (SIT) were compared with 4 days of prolonged sitting with a 1-h bout of treadmill exercise (SIT + EX; 63.1 ± 5.2% V̇o 2max ) on the evening of the fourth day. The following morning, participants completed a high-fat/glucose tolerance test (HFGTT), during which plasma was collected over a 6-h period and analyzed for triglycerides, glucose, and insulin. No differences between trials ( P > 0.05) were found in the overall plasma triglyceride, glucose, or insulin responses during the HFGTT. This lack of difference between trials comes with similarly low physical activity (~3,500-4,000 steps/day) on each day except for the 1-h bout of exercise during SIT + EX the day before the HFGTT. These data indicate that physical inactivity (e.g., sitting ~13.5 h/day and <4,000 steps/day) creates a condition whereby people become "resistant" to the metabolic improvements that are typically derived from an acute bout of aerobic exercise (i.e., exercise resistance). NEW & NOTEWORTHY In people who are physically inactive and sitting for a majority of the day, a 1-h bout of vigorous exercise failed to improve lipid, glucose, and insulin metabolism measured the next day. It seems that something inherent to inactivity and/or prolonged sitting makes the body resistant to the 1 h of exercise preventing the normally derived metabolic improvements following exercise.

The decline in stroke volume (SV) during exercise in the heat has been attributed to either an increase in cutaneous blood flow (CBF) that reduces venous return or an increase in heart rate (HR) that reduces cardiac filling time. However, the evidence supporting each mechanism arises under experimental conditions with different skin temperatures (T sk ; e.g., ≥38°C vs. ≤36°C, respectively). We systematically studied cardiovascular responses to progressively increased T sk (32°C-39°C) with narrowing of the core-to-skin gradient during moderate intensity exercise. Eight men cycled at 63 ± 1% peak oxygen consumption for 20-30 min. T sk was manipulated by having subjects wear a water-perfused suit that covered most of the body and maintained T sk that was significantly different between trials and averaged 32.4 ± 0.2, 35.5 ± 0.1, 37.5 ± 0.1, and 39.5 ± 0.1°C, respectively. The graded heating of T sk ultimately produced a graded elevation of esophageal temperature (T es ) at the end of exercise. Incrementally increasing T sk resulted in a graded increase in HR and a graded decrease in SV. CBF reached a similar average plateau value in all trials when T es was above ~38°C, independent of T sk . T sk had no apparent effect on forearm venous volume (FVV). In conclusion, the CBF and FVV responses suggest no further pooling of blood in the skin when T sk is increased from 32.4°C to 39.5°C. The decrease in SV during moderate intensity exercise when heating the skin to high levels appears related to an increase in HR and not an increase in CBF. NEW & NOTEWORTHY This study systematically investigated the effect of increasing skin temperature (T sk ) to high levels on cardiovascular responses during moderate intensity exercise. We conclude that the declines in stroke volume were related to the increases in heart rate but not the changes in cutaneous blood flow (CBF) and forearm venous volume (FVV) during moderate intensity exercise when T sk increased from ~32°C to ~39°C. High T sk (≥38°C) did not further elevate CBF and FVV compared with lower T sk during moderate intensity exercise.

The interaction of prolonged sitting with physical exercise for maintaining health is unclear. We tested the hypothesis that prolonged siting would have a deleterious effect on postprandial plasma lipemia (PPL, postprandial plasma triglycerides) and reduce the ability of an acute exercise bout to attenuate PPL. Seven healthy young men performed three, 5-day interventions [days 1-5 (D1-D5)] in a randomized crossover design with >1 wk between interventions: 1) sitting > 14 h/day with hypercaloric energy balance (SH), 2) sitting >14 h/day with net energy balance (SB), and 3) active walking/standing with net energy balance (WB) and sitting 8.4 h/day. The first high-fat tolerance test (HFTT1) was performed on D3 following 2 days of respective interventions. On the evening of D4 subjects ran on a treadmill for 1 h at ~67% V̇o 2max , followed by the second HFTT (HFTT2) on D5. Two days of prolonged sitting increased TG AUC I (i.e., incremental area under the curve for TG), irrespective of energy balance, compared with WB (27% in SH, P = 0.003 and 26% in SB, P = 0.046). Surprisingly, after 4 days of prolonged sitting (i.e.; SH and SB), the acute exercise on D4 failed to attenuate TG AUC I or increase relative fat oxidation in HFTT2, compared with HFTT1, regardless of energy balance. In conclusion, prolonged sitting over 2-4 days was sufficient to amplify PPL, which was not attenuated by acute exercise, regardless of energy balance. This underscores the importance of limiting sitting time even in people who have exercised., (Copyright © 2016 the American Physiological Society.)

The evaluation of gender nonconformity in children was examined in two studies. In Study 1, 48 young adults evaluated the positivity of culturally popular labels for gender nonconformity, including "tomboy," "sissy," and two new labels generated in a pilot study, "mama's boy" and "brat." The "mama's boy" was described as a boy who has positive feminine traits (gentle and well-mannered) as opposed to the "sissy" who was described as having negative feminine traits (crying and easily frightened). In Study 2, 161 young adults read descriptions of gender-typical and nonconforming children, evaluating them in several domains. The label "mama's boy" was considered negative in Study 1 but an unlabeled positive nonconforming boy was rated as likable and competent in Study 2. However, participants worried about nonconforming boys, saying they would encourage them to behave differently and describing such children with derogatory sexual orientation slurs. "Tomboy" was generally considered a positive label in Study 1. In Study 2, gender nonconforming girls were considered neither likable nor dislikeable, and neither competent nor incompetent, reflecting ambivalence about girls' nonconformity. It may be that we use gender nonconformity labels as indicators of sexual orientation, even in young children. Therefore, even when an individual displays objectively positive traits, the stigma associated with homosexuality taints judgments about their nonconforming behavior.

Gender schema theory (GST) posits that children approach opportunities perceived as gender appropriate, avoiding those deemed gender inappropriate, in turn affecting gender-differentiated career trajectories. To test the hypothesis that children's gender salience filters (GSF-tendency to attend to gender) moderate these processes, 62 preschool girls (M = 4.5 years) were given GSF measures. Two weeks later, they played a computer game about occupations that manipulated the game-character's femininity (hyperfeminized Barbie vs. less feminized Playmobil Jane). Following game play, girls' interests in feminine activities showed an interaction of game condition and GSF: High-GSF girls showed intensified feminine activity interests only with Barbie; low-GSF girls showed no change with either character. Neither GSF nor game condition affected occupational interests. Implications for GST, individual differences, and occupational interventions are discussed., (© 2015 The Authors. Child Development © 2015 Society for Research in Child Development, Inc.)

Purpose: Exercise in hot conditions increases core (TC) and skin temperature (TSK) and can lead to a progressive rise in HR and decline in stroke volume (SV) during prolonged exercise. Thermoregulatory-driven elevations in skin blood flow (SkBF) adds complexity to cardiovascular regulation during exercise in these conditions. Presently, the dominant, although debated, view is that raising TSK increases SkBF and reduces SV through diminished venous return; however, this scenario has not been rigorously investigated across core and skin temperatures. We tested the hypothesis that high TSK would raise HR and reduce SV during exercise after precooling (cold water bath) and preheating (hot water bath) and that no relationship would exist between SkBF and SV during exercise., Methods: Non-endurance-trained individuals cycled for 20 min at 69% ± 1% VO₂peak on four occasions: cool skin-cool core (SkCCC), warm skin-cool core (SkWCC), cool skin-warm core (SkCCW), and warm skin-warm core (SkWCW) on separate days., Results: After precooling of TC, the rise in HR was greater in SkWCC than in SkCCC (P < 0.001), yet SV was similar (P = 0.26), which resulted in higher QC at min 20 in SkWCC (P < 0.01). Throughout exercise after preheating of TC, HR was higher (P < 0.001), SV was reduced (P < 0.01), and QC was similar (P = 0.40) in SkWCW versus SkCCW. When all trials were compared, there was no relationship between SkBF and SV (r = -0.08, P = 0.70); however, there was an inverse relationship between HR and SV (r = -0.75, P < 0.001)., Conclusions: These data suggest that when TSK is elevated during exercise, HR and TC will rise but SV will only be reduced when TC is also elevated above 38°C. Furthermore, changes in SV are not related to changes in SkBF.

Unlabelled: Acute endurance exercise has been shown to lower postprandial plasma triglyceride (PPTG) concentrations; however, whether this is due to the negative energy and/or CHO deficit from the exercise bout is not well understood., Purpose: This study aimed to examine the effects of a postexercise meal consisting of either high or low CHO content on PPTG and postprandial fat oxidation the morning after an exercise bout., Methods: Healthy young men (n = 6) performed each of four experimental treatments: 1) nonexercise control (CON), 2) 80 min of cycling with either no meal replacement (EX), 3) a high-CHO postexercise meal (EX+HCHO), or a 4) low-CHO postexercise meal (EX+LCHO). A standardized meal for PPTG determination was provided (16.0 kcal · kg(-1) body mass, 1.02 g fa t · kg(-1), 1.36 g CHO · kg(-1), 0.31 g protein · kg(-1)) 12 h after the exercise, and measurements of plasma triglyceride (TG) concentration and whole-body resting fat oxidation were made in the fasted condition and during the 4-h postprandial period., Results: The total area under the curve for plasma TG was significantly lower in EX+LCHO (325 (63) mg · dL(-1) per 4 h) compared with that in EX+HCHO (449 (118) mg · dL(-1) per 4 h, P = 0.03). Postprandial fat oxidation during this period was significantly greater in EX+LCHO (257 (58) kcal per 4 h, P = 0.003) compared with that in EX+HCHO (209 (56) kcal per 4 h). The change in total postprandial fat oxidation (kcal per 4 h) relative to CON was significantly and inversely correlated with the change in the total TG area under the curve relative to CON (mg · dL(-1) per 4 h, ΔTG AUC, R2 = 0.37, P = 0.008)., Conclusions: The low CHO composition of the postexercise meal contributes to lower PPTG and increased fat oxidation, with lower PPTG related to an increase in fat oxidation.

Unlabelled: The elevation of postprandial plasma triglycerides (PPTG) in the blood is an independent risk factor for atherosclerosis. Although acute exercise typically attenuates PPTG, the effect of exercise intensity on PPTG is less well established, particularly in well-controlled conditions for physical activities and diet., Purpose: We sought to determine the efficacy of exercise at 65% V˙O2max with an extended sitting time and isoenergetic intermittent walking exercise at a self-selected walking speed (approximately 25% V˙O2max) on PPTG compared with that of a sitting control condition. In a randomized crossover design, nine healthy young men completed three trials with a >1-wk interval between trials. After 2 d of activity and diet normalization, participants performed prolonged sitting nonexercise control (CON), prolonged sitting with subsequent 1-h running at 65% V˙O2max (MOD), or isoenergetic intermittent walking at approximately 25% V˙O2max (LOW) on day 3. This was followed on day 4 by a 6-h high-fat tolerance test., Results: MOD and LOW reduced incremental triglyceride (TG) area under the curve (TG AUCI) compared with that in CON by 33.6% (P < 0.005) and 19.8% (P < 0.05), respectively. MOD also reduced TG AUCI compared with that in LOW by 17.2% (P < 0.03). The reduced TG AUCI in MOD was accompanied by reduced plasma glucose response and enhanced fat oxidation compared with those in LOW and CON (for all, P < 0.05), respectively., Conclusions: Both MOD and LOW were effective in reducing PPTG compared with CON. However, MOD was more effective in reducing PPTG compared with LOW.

This investigation sought to determine if supplementation with polyphenol antioxidant (PA) improves exercise performance in the heat (31.5 °C, 55% RH) by altering the cardiovascular and thermoregulatory responses to exercise. Twelve endurance trained athletes ingested PA or placebo (PLAC) for 7 days. Consecutive days of exercise testing were performed at the end of the supplementation periods. Cardiovascular and thermoregulatory measures were made during exercise. Performance, as measured by a 10 min time trial (TT) following 50 min of moderate intensity cycling, was not different between treatments (PLAC: 292 ± 33 W and PA: 279 ± 38 W, p = 0.12). Gross efficiency, blood lactate, maximal neuromuscular power, and ratings of perceived exertion were also not different between treatments. Similarly, performance on the second day of testing, as assessed by time to fatigue at maximal oxygen consumption, was not different between treatments (PLAC; 377 ± 117 s vs. PA; 364 ± 128 s, p = 0.61). Cardiovascular and thermoregulatory responses to exercise were not different between treatments on either day of exercise testing. Polyphenol antioxidant supplementation had no impact on exercise performance and did not alter the cardiovascular or thermoregulatory responses to exercise in the heat.

Women and girls in the United States continue to be underrepresented in STEM, particularly in engineering and technology fields. This gap has been attracting recent attention from those motivated to ensure that girls and women have access to a full range of personally satisfying careers as well as from those concerned with developing a rich talent pool to meet national workforce needs. This chapter is focused on interventions that have been designed to address this STEM gender gap. We begin by documenting the STEM gender gap and then review change mechanisms emerging from theories of gender development that may be harnessed in intervention efforts. In addition, we pro vide a taxonomy of intervention goals which we then use to organize an illustrative review of sample interventions. After commenting on some of the findings and limitations of past work, we offer suggestions for enhancing the systematic evaluation of intervention programs that include careful selection of comparison groups, a broad array of STEM outcome measures, assessment of potentially unintended consequences, and meta-analyses.

Acute exercise has been shown to attenuate postprandial plasma triglyceride elevation (PPTG). However, the direct contribution of exercise intensity is less well understood. The purpose of this study was to examine the effects of exercise intensity on PPTG and postprandial fat oxidation. One of three experimental treatments was performed in healthy young men (n = 6): nonexercise control (CON), moderate-intensity exercise (MIE; 50% Vo2peak for 60 min), or isoenergetic high-intensity exercise (HIE; alternating 2 min at 25% and 2 min at 90% Vo2peak). The morning after the exercise, a standardized meal was provided (16 kcal/kg BM, 1.02 g fat/kg, 1.36 g CHO/kg, 0.31 g PRO/kg), and measurements of plasma concentrations of triglyceride (TG), glucose, insulin, and β-hydroxybutyrate were made in the fasted condition and hourly for 6 h postprandial. Indirect calorimetry was used to determine fat oxidation in the fasted condition and 2, 4, and 6 h postprandial. Compared with CON, both MIE and HIE significantly attenuated PPTG [incremental AUC; 75.2 (15.5%), P = 0.033, and 54.9 (13.5%), P = 0.001], with HIE also significantly lower than MIE (P = 0.03). Postprandial fat oxidation was significantly higher in MIE [83.3 (10.6%) of total energy expenditure] and HIE [89.1 (9.8) %total] compared with CON [69.0 (16.1) %total, P = 0.039, and P = 0.018, respectively], with HIE significantly greater than MIE (P = 0.012). We conclude that, despite similar energy expenditure, HIE was more effective than MIE for lowering PPTG and increasing postprandial fat oxidation.

The purpose of this study was to investigate how maximal power output (PMAX), as measured via the inertial load cycling technique, changes throughout a collegiate soccer season in relation to training load completed. The current investigation took place throughout the 2010 Big XII soccer season. Nineteen Division I female collegiate soccer players (age: 19.9 ± 1.2 years, stature: 165.1 ± 6.6 cm, mass: 61.0 ± 6.8 kg) from the same team completed regular inertial load cycling tests and perceptual fatigue questionnaires throughout the season. Players were divided into STARTERS and NON-STARTERS based on percentage of matches started throughout the season. The results demonstrated that STARTERS experience much greater load throughout the season than NON-STARTERS (2247 ± 176 arbitrary units [AU] and 1585 ± 174 AU, p < 0.05), accounted for by increased load during matches. This increased load throughout the season was accompanied by decline in PMAX in STARTERS (to 92.3 ± 6.6%, p < 0.05), whereas PMAX was maintained in NON-STARTERS for the duration of the season (99.0 ± 4.9%). Furthermore, STARTERS experienced greater muscle soreness throughout the in-season period compared with NON-STARTERS. The main finding of this study is that PMAX declined throughout the middle and latter parts of the season in STARTERS, after experiencing significantly greater match loads than NON-STARTERS throughout the season. The current findings, combined with previous investigations, suggest that load needs to be carefully monitored throughout the in-season period to maintain optimal neuromuscular performance throughout a team's entire sporting season.

Aim: Recent findings have challenged the belief that the cardiac output (CO) and oxygen consumption (VO(2) ) relationship is linear from rest to maximal exercise. The purpose of this study was to determine the CO and stroke volume (SV) response to a range of exercise intensities, 40-100% of VO(2max), during cycling., Methods: Ten well-trained cyclists performed a series of discontinuous exercise bouts to determine the CO and SV vs. VO(2) responses., Results: The rate of increase in CO, relative to VO(2) , during exercise from 40 to 70% of VO(2max) was 4.4 ± 1.4 L L(-1). During exercise at 70-100% of VO(2max) , the rate of increase in CO was reduced to 2.1 ± 0.9 L L(-1) (P = 0.01). Stroke volume during exercise at 80-100% of VO(2max) was reduced by 7% when compared to exercise at 50-70% of VO(2max) (134 ± 5 vs. 143 ± 5 mL per beat, P = 0.02). Whole body arterial-venous O(2) difference increased significantly as intensity increased., Conclusion: The observation that the rate of increase in CO is reduced as exercise intensity increases suggests that cardiovascular performance displays signs of compromised function before maximal VO(2) is reached., (© 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.)

The purpose of this study was to analyze pedaling cadence, pedal forces, and muscle activation of triathletes during cycling to exhaustion. Fourteen triathletes were assessed at the power output level relative to their maximal oxygen uptake (355 +/- 23 W). Cadence, pedal forces, and muscle activation were analyzed during start, middle, and end test stages. Normal and tangential forces increased from the start to the end of the test (-288 +/- 33 to -352 +/- 42 N and -79 +/- 45 to -124 +/- 68 N, respectively) accompanied by a decrease in cadence (96 +/- 5 to 86 +/- 6 rpm). Muscle activation increased from the start to the middle and the end in the gluteus maximus (27 +/- 5.5% and 76 +/- 9.3%) and in the vastus lateralis (13 +/- 3.5% and 27 +/- 4.4%), similar increase was observed from the start to the end in the rectus femoris and the vastus medialis (50 +/- 9.3% and 20 +/- 5.7%, respectively). Greater normal force along with enhanced activation of knee and hip extensor muscles is linked with fatigue and declines in cadence of triathletes during cycling to exhaustion.

The purpose of this study was to determine if pomegranate juice supplementation improved the recovery of skeletal muscle strength after eccentric exercise in subjects who routinely performed resistance training. Resistance trained men (n = 17) were randomized into a crossover design with either pomegranate juice or placebo. To produce delayed onset muscle soreness, the subjects performed 3 sets of 20 unilateral eccentric elbow flexion and 6 sets of 10 unilateral eccentric knee extension exercises. Maximal isometric elbow flexion and knee extension strength and muscle soreness measurements were made at baseline and 2, 24, 48, 72, 96, and 168 hours postexercise. Elbow flexion strength was significantly higher during the 2- to 168-hour period postexercise with pomegranate juice compared with that of placebo (main treatment effect; p = 0.031). Elbow flexor muscle soreness was also significantly reduced with pomegranate juice compared with that of placebo (main treatment effect; p = 0.006) and at 48 and 72 hours postexercise (p = 0.003 and p = 0.038, respectively). Isometric strength and muscle soreness in the knee extensors were not significantly different with pomegranate juice compared with those using placebo. Supplementation with pomegranate juice attenuates weakness and reduces soreness of the elbow flexor but not of knee extensor muscles. These results indicate a mild, acute ergogenic effect of pomegranate juice in the elbow flexor muscles of resistance trained individuals after eccentric exercise.

Participants were 150 school-age boys and girls, 58 high school students, and 145 university students drawn from communities in the Southeastern United States. In this cross-sectional study, family role attitudes and expectations were examined across development. Parental work traditionality (occupational prestige and traditionality, and employed hours) predicted daughters' social role attitudes and plans for future family roles, such that daughters' envisioned families resembled that of their parents. Sons' and daughters' own attitudes about adult family roles predicted their plans to work or stay home with their future children; however, mothers' work traditionality predicted daughters' future plans over and above daughters' own attitudes. The only exception to this was in the case of university daughters, where university women's attitudes about social roles fully mediated this relationship. It may be that, as young women approach adulthood and the formation of families, they adjust their vision of their future self to match more closely their own attitudes about the caregiving role.

Purpose: This study determined if changes in serum sodium concentration are related to fluid balance as well as sweat sodium losses in triathletes competing in the Hawaii Ironman triathlon., Methods: Endurance trained athletes (N = 46, age = 24-67 yr) were studied during 30 min of stationary cycling at 70%-75% of HRmax in a warm outdoor laboratory (26.4 degrees C +/- 1.7 degrees C wet bulb globe temperature [WBGT], 28.3 degrees C +/- 1.2 degrees C dry bulb [DB]) 3-7 d before race day. Sweat sodium concentration was measured from absorbent patches on the forearm and scapula, and sweating rate was derived from changes in body mass. Before and after the race, serum sodium concentration, body mass, and nutritional intake during the race were also measured (N = 46). Sweating and race day comparisons and changes in serum sodium concentration were analyzed via Student's t-test, correlation, and multiple regression., Results: In men, the change in serum sodium concentration during the race was correlated with relative sweating rate (mL.kg.h; r = -0.49, P = 0.012), rate of sweat sodium loss (mEq.kg.h; r = -0.44, P = 0.023), and body mass change (kg; r = -0.54, P = 0.005). Together, the rate of sweat sodium loss and body mass change accounted for 46% of the change in serum sodium concentration in men (R = 0.46). In women, body mass change alone was significantly correlated with the change in serum sodium concentration (r = 0.31). The rate of sodium intake (mEq.kg.h) was related to the rate of sweat sodium loss in women (mEq.kg.h; r = 0.64, P = 0.035) but not in men (r = 0.27, P = 0.486)., Conclusion: Changes in serum sodium concentration during an ultraendurance triathlon are significantly related to interactions of fluid balance, sweat sodium loss, and sodium ingestion.

People who become hyperthermic during exercise display large increases in heart rate (HR) and reductions in stroke volume (SV). It is not clear if the reduction in SV is due primarily to hyperthermia or if it is a secondary effect of an elevation in HR reducing ventricular filling. In the present study, the upward drift of HR during prolonged exercise was prevented by a very small dose of the β1-adrenoreceptor blocker (atenolol; βB), thus allowing SV to be compared at a given HR during normothermia and hyperthermia. Eleven men cycled for 60 min at 57% of peak O2 uptake after receiving placebo control (PL) or a low dose (0.2 mg/kg) of βB. Hyperthermia was induced by reducing heat dissipation during exercise. Four experimental conditions were studied: normothermia-PL, normothermia-βB, hyperthermia-PL, and hyperthermia-βB. Hyperthermia increased skin and core temperature by 4.3 degrees C and 0.8 degrees C (P<0.01), respectively. βB prevented HR elevation with hyperthermia: HR values were similar at minute 60 during normothermia-PL and hyperthermia-βB (155±11 and 154±13 beats/min, respectively, P=0.82). However, SV was increased by 7% during the final 20 min of exercise during hyperthermia-βB compared with normothermia-PL (treatment×time interaction, P=0.03). In conclusion, when matched for HR, mild hyperthermia increased SV during exercise. Furthermore, the reduction in SV throughout prolonged exercise under normothermic and mildly hyperthermic conditions appears to be due to the increase in HR.

An overnight fast of 8-10 h is normal for most people. Fasting is characterised by a coordinated set of metabolic changes designed to spare carbohydrate and increase reliance on fat as a substrate for energy supply. As well as sparing the limited endogenous carbohydrate, and increased rate of gluconeogenesis from amino acids, glycerol and ketone bodies help maintain the supply of carbohydrate. Many individuals undergo periodic fasts for health, religious or cultural reasons. Ramadan fasting, involving 1 month of abstention from food and fluid intake during daylight hours, is practised by a large part of the world population. This period involves a shift in the pattern of intake from daytime to the hours of darkness. There seems to be little effect on overall daily dietary intake and only small metabolic effects, but there may be implications for both physical and cognitive function. The limited evidence suggests that effects of Ramadan-style fasting on exercise performance are generally small. This needs to be balanced, however, against the observation that small differences in performance are critical in determining the outcomes of sporting events. Studies involving challenging sporting events (prolonged sustained or intermittent high-intensity events, hot and humid environments) are needed. Increases in subjective sensations of fatigue may be the result of loss of sleep or disruption of normal sleep patterns. Modifications to the competition timetable may minimise or even eliminate any effect on performance in sport, but there may be negative effects on performance in some events.

Purpose: Dietary supplementation with polyphenols,particularly ellagitannins, may attenuate the muscular damage experienced after eccentric exercise, producing delayed-onset muscle soreness. The purpose of this study was to determine whether ellagitannin supplementation from Wonderful variety pomegranate extract (POMx) improved recovery of skeletal muscle strength after eccentric exercise., Methods: Recreationally active males were randomized into a crossover design with either pomegranate extract (POMx) or placebo (PLA), each given during a period of 9 d.To produce delayed-onset muscle soreness, subjects performed two sets of 20 maximal eccentric elbow flexion exercises with one arm.Maximal isometric elbow flexion strength and muscle soreness as well as serum measures of creatine kinase, myoglobin, interleukin 6, and C-reactive protein were made at baseline and 2, 24, 48, 72, and 96 h after exercise., Results: With both treatments, strength was similarly reduced 2 h after exercise (i.e., 72% of baseline), and recovery of strength was incomplete after 96 h (i.e., 91% of baseline).However, strength was significantly higher in POMx compared with that in PLA at 48 h (85.4% +/- 2.5% and 78.3% +/- 2.6%, P = 0.01) and 72 h (88.9% +/- 2.0% and 84.0% +/- 2.0%, P = 0.009) after exercise. Serum markers of inflammation and muscle damage did not provide insight regarding possible mechanisms., Conclusions: Supplementation with ellagitannins from pomegranate extract significantly improves recovery of isometric strength 2-3 d after a damaging eccentric exercise.

This study examined how altering training intensity during a taper impacts maximal mechanical power (Pmax), torque at power maximum (T), velocity at power maximum (V), and swim performance (m . sec (-1)). Using an arm ergometer with inertial loading, measurements of Pmax, T, and V were made for 7 consecutive weeks prior to the taper and during the taper in 7 female competitive collegiate swimmers. Subjects were tested over two consecutive years. Swim performance was obtained from 3 competitive meets; a conference meet (CM), the conference championship meet (CONF) and the national championship meet (NAT). A 50 to 60 % increase in the amount of "high-intensity training" during the taper of 2005 (High-Intensity Taper - HIT) resulted in Pmax values that were 8 to 14 % higher (40 to 60 Watts) at all but one time point when compared to the 2004 taper (Low-Intensity Taper - LIT). Swim performance was significantly worsened at the NAT following LIT. However, with the HIT, swim performance, Pmax, and T were maintained prior to and at NAT. A large reduction in high-intensity training during a taper reduces the length of time that Pmax, T, and swim performance can be maintained at peak levels.

Efforts to understand human physiology through the study of champion athletes and record performances have been ongoing for about a century. For endurance sports three main factors--maximal oxygen consumption (.VO(2,max)), the so-called 'lactate threshold' and efficiency (i.e. the oxygen cost to generate a given running speed or cycling power output)--appear to play key roles in endurance performance. and lactate threshold interact to determine the 'performance .VO(2)' which is the oxygen consumption that can be sustained for a given period of time. Efficiency interacts with the performance .VO(2) to establish the speed or power that can be generated at this oxygen consumption. This review focuses on what is currently known about how these factors interact, their utility as predictors of elite performance, and areas where there is relatively less information to guide current thinking. In this context, definitive ideas about the physiological determinants of running and cycling efficiency is relatively lacking in comparison with .VO(2,max) and the lactate threshold, and there is surprisingly limited and clear information about the genetic factors that might pre-dispose for elite performance. It should also be cautioned that complex motivational and sociological factors also play important roles in who does or does not become a champion and these factors go far beyond simple physiological explanations. Therefore, the performance of elite athletes is likely to defy the types of easy explanations sought by scientific reductionism and remain an important puzzle for those interested in physiological integration well into the future.