Effects of intermittent hypoxia training on exercise performance, hemodynamics, and ventilation in healthy senior men

The efficacy and safety of intermittent hypoxia training (IHT) were investigated in healthy, 60- to 74-yr-old men. Fourteen men (Gr 1) who routinely exercised daily for 20 to 30 min were compared with 21 (Gr 2) who avoided exercise. Their submaximal work-load power values before the IHT training were 94 +/- 3.7 and 66 +/- 3.1, respectively. Before and after 10 days of IHT, the ventilatory response to sustained hypoxia (SH; 12% O(2) for 10 min), work capacity (bicycle ergometer), and forearm cutaneous perfusion (laser Doppler) were determined. During SH, no negative electrocardiogram (ECG) changes were observed in either group, and the ventilatory response to SH was unaltered by IHT. In Gr 1, IHT (normobaric rebreathing for 5 min, final Sa(O(2)) = 85% to 86%, followed by 5 min normoxia, 4/day) produced no changes in hemodynamic indixes and work capacity. In Gr 2, IHT decreased blood pressure (BP) by 7.9 +/- 3.1 mmHg (p < 0.05) and increased submaximal work by 11.3% (p < 0.05) and anaerobic threshold by 12.7% (p < 0.05). The increase in HR and BP caused by a 55 W-work load was reduced by 5% and 6.5%, respectively (p < 0.05). Cutaneous perfusion increased by 0.06 +/- 0.04 mL/min/100 g in Gr 1 and by 0.11 +/- 0.04 mL/min/100 g in Gr 2 (p < 0.05). Hyperemia recovery time increased significantly by 15.3 +/- 4.6 sec in Gr 1 and by 25.2 +/- 11.2 sec in Gr 2. Thus, healthy senior men well tolerate IHT as performed in this investigation. In untrained, healthy senior men, IHT had greater positive effects on hemodynamics, microvascular endothelial function, and work capacity.     

Comparative echocardiographic study of junior and senior basketball players

The echocardiographic data on 14 junior and 15 senior players in a first-division basketball club were compared. No difference was found between the senior and junior players as regards the thickness of the interventricular septum (11.47 vs 11.21 mm) or the thickness of the posterior wall of the left ventricle (9.8 vs 9.86 mm). The adults displayed a larger left ventricular end-diastolic diameter (56.8 vs 53.6 mm, P less than 0.05), end-diastolic volume (194 vs 164 ml, P less than 0.05), stroke volume (142 vs 116 ml, P less than 0.05), right ventricular diameter (27.9 vs 23.2, P less than 0.01), aortic root diameter (35.0 vs 32.0, P less than 0.05), and left atrial diameter (42.7 vs 37.2, P less than 0.01). However, among these, only the stroke volume and right ventricular diameter remained significantly different after normalization to body surface area. A significant difference could not be demonstrated in the linear ejection fraction, the ejection fraction, or the fractionated interventricular septum and posterior wall thicknesses. The examinations indicated that left ventricular hypertrophy had fully developed by the age of 18 years in the basketball players and that there was no further enhancement in adults. However, the left ventricular, right ventricular, and left atrial volume were larger in the adults than in the junior players.     

Determinants of five kilometre running performance in active men and women.

Previous studies of elite endurance athletes have suggested that success in distance running is attributable to the possession of a high maximal oxygen uptake (VO2 max), the utilisation of a large fraction of the VO2 max and to running economy. The purpose of the present study was to examine the relationships between these physiological characteristics and running performance in active but not elite men and women. Maximal oxygen uptake values were 57.6 +/- 6.2 and 46.6 +/- 4.8 ml . kg.-1 min-1 for the men and women respectively (p less than 0.01). Running performance was assessed as a 5 km time trial and the men completed this distance in 19.77 +/- 2.27 min and the women in 24.44 +/- 3.19 min (p less than 0.01). Maximal oxygen uptake showed strong correlations (p less than 0.01) with running performance (men, r = -0.85; women, r = -0.80) but there was only a modest relationship between running economy and performance (men, r = 0.39; women, r = 0.34). The results of the present study suggest that the faster 5 km performance times recorded by the men were best explained by their higher VO2 max values.     

Physiological characteristics of junior and senior rugby league players

OBJECTIVES: To investigate the physiological characteristics of subelite junior and senior rugby league players and establish performance standards for these athletes. METHODS: A total of 159 junior (under 16, 15, 14, and 13, n = 88) and senior (first grade, second grade, and under 19, n = 71) rugby league players (forwards, n = 80, backs, n = 79), competing at a subelite level, underwent measurements of body mass, muscular power (vertical jump), speed (10 m, 20 m, and 40 m sprint), agility (Illinois agility run), and estimated maximal aerobic power (multistage fitness test). Data were also collected on match and training frequency and playing experience. RESULTS: There was a significant effect (p<0.05) of age and playing level on playing experience, body mass, muscular power, speed, agility, and estimated maximal aerobic power, with the physiological capacities of players increasing as the playing level increased. Forwards were heavier than backs for all junior and senior teams. Forwards and backs had similar estimated maximal aerobic power, except for under 16 players, for whom significant (p<0.05) differences were detected (mean (95% confidence intervals) 42.9 (40.1 to 45.7) v 49.5 (46.4 to 52.6) ml/kg/min for forwards and backs respectively). Scores for speed, muscular power, and agility were not significantly different between forwards and backs for any of the junior or senior teams. CONCLUSIONS: The results show that there is a progressive improvement in the physiological capacities of rugby league players as the playing level increases. These findings provide normative data and performance standards for subelite junior and senior rugby league players. Further studies on the sociological, physical, psychological, and personal predictors of talent in rugby league are warranted.     

Incidence of injury in junior and senior rugby league players

Rugby league is an international collision sport played at junior, amateur, semi-professional and professional levels. Due to the high numbers of physical collisions and tackles, musculoskeletal injuries are common. A large percentage of injuries result in long-term employment and study limitations, medical costs and loss of income. Review articles addressing the applied physiology of rugby league and common rugby league injuries have been published. However, both of these review articles have focused on the professional rugby league player. This review addresses the extent of the injury problem in rugby league in all levels of competition (i.e. junior, amateur, semi-professional and professional). The incidence of rugby league injuries typically increases as the playing level is increased. The majority of studies have shown that the head and neck is the most common site of match injuries in senior rugby league players, while knee injuries are the most common site of injury in junior rugby league players. Muscular injuries are the most common type of injury sustained by senior rugby league players, while junior rugby league players more commonly sustain fractures. Injuries are most commonly sustained in tackles, by the tackled player. Thigh and calf strains are the most common injuries sustained during rugby league training, while overexertion is the most common cause of training injuries. Player fatigue may influence the incidence of injury, with most sub-elite (amateur and semi-professional) rugby league injuries occurring in the second half of matches or the latter stages of training sessions. The majority of training injuries occur in the early stages of the season, while match injuries occur in the latter stages of the season, suggesting that changes in training and playing intensity may influence the incidence of injury in rugby league. Injury prevention studies are required to reduce the incidence, severity and cost of rugby league injuries. These injury prevention strategies could include coaching on defensive skills, correct tackling technique, correct falling technique and methods to minimise the absorption of impact forces in tackles. Game-specific attacking and defensive drills practised before and during fatigue may also encourage players to make appropriate decisions under fatigued conditions and apply learnt skills during the pressure of competitive matches. Further studies investigating risk factors for injury in junior and senior rugby league players, injuries sustained by specific playing positions and the influence of injuries on playing performance are warranted.     

Running performance differences between men and women:an update

More than a decade ago it was reported in the journal Nature that the slope of improvement in the men's and women's running records, extrapolated from mean running velocity plotted against historical time, would eventually result in a performance intersection of the sexes across a variety of running distances. The first of these intersections was to occur for 42 000 m before the 21st century. Most of the error in this prediction is probably explained by the linear mathematical treatment and extrapolation of limited performance data, since including world record-setting running performances for women before and after 1985 results in a non-linear data fit. The reality of early, disproportionate improvements in women's running that gave the appearance of an impending convergence with men is best explained by an historical social sports bias. Women's times have now reached a plateau similar to that observed for men at comparative performance milestones in the marathon. Sex differences at distances from 100 to 10 000 m show similar trends. The remaining sex gaps in performance appear biological in origin. Success in distance running and sprinting is determined largely by aerobic capacity and muscular strength, respectively. Because men possess a larger aerobic capacity and greater muscular strength, the gap in running performances between men and women is unlikely to narrow naturally.     

Physical attributes,limitations, and future potential for PET and SPECT

Background  

Cadmium Zinc Telluride (CZT) SPECT camera technology has the potential to reduce patient’s radiation exposure and shorten imaging time. This study evaluated the correlation of low stress tracer dose, rapid CZT SPECT myocardial perfusion imaging (MPI) to coronary angiography in a <200-lbs population to further validate its ability to achieve both goals while preserving diagnostic accuracy.     

Physical attributes, limitations, and future potential for PET and SPECT

Advances in SPECT and PET imaging hardware, software, and radiotracers are vastly improving the non-invasive evaluation of myocardial perfusion and function. In contrast to traditional dual-headed, sodium iodide crystal and photomultiplier cameras with mechanical collimators, new SPECT camera designs utilize novel, collimators, and solid-state detectors that convert photons directly to electrical signals. These cameras simultaneously collect data from as many as 76 small detectors narrowly focused on the heart. New noise regularization and resolution recovery/noise reduction reconstruction software interprets emitted counts more efficiently and thus more effectively discriminates between useful signals and noise. As a result, shorter acquisition times and/or lower tracer doses produce higher quality SPECT images than were possible before. PET perfusion imaging has benefitted from the introduction of novel detectors that now allow true 3D imaging, new radiopharmaceuticals, and precise attenuation correction (AC). These developments have resulted in perfusion images with higher spatial and contrast resolution that may be acquired in shorter protocols and/or with less patient radiation exposure than traditional SPECT. Hybrid SPECT/CT and PET/CT cameras utilize transmission computed tomographic (CT) scans for AC, and offer the additional clinical advantages of evaluating coronary calcium, myocardial anatomy (including non-invasive CT angiography), myocardial function, and myocardial perfusion in a single imaging procedure.     

Attentional focus and mental skills in senior and junior professional rugby union players

Objective

The aim of the present study was to examine possible differences in attentional focus and mental skills depending on athlete’s experience.

Method

Forty-seven junior sub-elite, between ages of 15 and 18 years (M = 15.77, SD = 0.84) and 43 senior elite rugby union players, between ages of 20 and 37 years (M = 26.40, SD = 4.88), participated in this study. We measured attentional focus and mental skills using a short version of the Test of Attentional and Interpersonal Styles and the Sport Performance Psychological Inventory.

Results

The results showed statistically significant differences between the groups for one of the mental skills examined and for all the attentional focus dimensions, evidencing consistently more functional psychological profiles for the more experienced groups.

Conclusions

Data suggest that attentional focus skills increase with experience. Future research directions and practical implications are discussed.     

Comparison of left ventricular performance in healthy young women and men during exercise

Background

Previous studies show sex-related differences in left ventricular (LV) response to exercise. It is not clear, however, whether these differences are also seen in younger healthy subjects.

Methods and Results

This study examined the changes in LV performance during dynamic upright exercise in 11 healthy men and 19 healthy young women according to the Bruce protocol and an individualized ramp protocol. There were no significant differences between the two protocols for either men or women in heart rate, blood pressure, LV ejection fraction (EF) (measured by ambulatory nuclear detector), and measured oxygen consumption. The peak oxygen consumption was higher in men than in women (44±13 vs 36±9 ml/kg/min; p<0.05), but the peak heart rate, systolic blood pressure, and EF were similar. The change in EF (from rest to exercise) was 19%±8% in men and 19%±11% in women with the Bruce protocol (difference not significant) and 26%±9% in men and 19%±6% in women with the ramp protocol (difference not significant). At peak exercise, both men and women showed an increase in end-diastolic volume (29%±14% vs 23%±11%; difference not significant) and a decrease in end-systolic volume (41%±15% vs 43%±21%) (difference not significant). The increase in cardiac output during exercise was due to an increase in heart rate and stroke volume in both men and women. At submaximal exercise, however, the decrease in end-systolic volume was less in women than in men (p<0.05).

Conclusions

There are no sex-related differences in compensatory mechanism during dynamic execise in healthy subjects. The changes in contractility and LV volume are not affected by the exercise protocol.     

The physiological responses to running after cycling in elite junior and senior triathletes

The purpose of this investigation was to compare the physiological responses in cycling and the energy cost (EC) of running after cycling in elite junior (J (male) and J (female)) and senior (S (male) and S (female)) triathletes and to determine the relationship between laboratory physiological parameters and performance in an elite "standard" distance triathlon. Thirty-one elite triathletes competing at World Championship level (age: 23.4 +/- 4.8 y; height: 172.6 +/- 6.8 cm; body mass: 64.4 +/- 7.2 kg; V.O (2)max = 67.8 +/- 8.3 ml x kg (-1) x min (-1)) comprising J (male) (n = 7), J (female) (n = 6), S (male) (n = 9) and S (female) (n = 9) athletes performed a laboratory trial that consisted of submaximal treadmill running (to determine EC), maximal then submaximal cycle ergometry (to determine the peak power output [PPO], V.O (2)max, the ventilation threshold [VT] and cycling economy) followed by an additional submaximal running bout. Swimming, cycling, running and overall race performance (min) over a standard event was also measured in the field. S (male) had a faster cycle, run and overall triathlon times than J (male). S (female) demonstrated a faster cycle and overall triathlon time than J (female). The V.O (2)max (74.7 +/- 5.7 vs. 74.3 +/- 4.4 and 60.1 +/- 1.8 vs. 61.0 +/- 5.0 ml x kg (-1) x min (-1)) and cycling economy (72.5 +/- 4.5 vs. 73.8 +/- 4.3 and 75.6 +/- 4.5 vs. 79.8 +/- 9.8 W x l (-1) x min (-1)) were similar between the junior and senior, in both male and female triathletes. However, S (female) possessed a significantly higher PPO than J (female). S (male) had a higher VT (%V.O (2)max) than J (male) whereas the VT was similar in J (female) and S (female). There were no significant differences in EC change from the first to the second running bout between J (male) and S (male), whereas, in contrast, J (female) exhibited a significantly (p < 0.05) higher difference in EC than S (female). When all subjects were pooled, the overall triathlon time (min) was significantly correlated to V.O (2)max (r = -0.80; p < 0.001) and PPO (W) (r = -0.85; p < 0.001) in cycle ergometry. In conclusion, elite senior triathletes can be distinguished from their younger (junior) counterparts, mainly by a higher PPO in cycling and a lower increase in the whole body energy cost of running after cycling in female and by a higher ventilatory threshold in male triathletes.     

Comparing sports injuries in men and women.

OBJECTIVE: To compare the pattern of injury between men and women in seven collegiate sports to determine if gender-specific factors exist which could be modified to reduce the risk of injury to female athletes. DESIGN: Retrospective cohort study of injury reports compiled by certified athletic trainers between Fall 1980 and Spring 1995. SETTING: An NCAA division III College. PARTICIPANTS: Eighteen to 22 year-old male and female college athletes competing in seven like sports (basketball, cross-country running, soccer, swimming, tennis, track and water polo) at the intercollegiate level, playing similar number of contests and using the same facilities. MAIN OUTCOME MEASURES: Analyses of injury patterns, classified by sport and anatomic location, for men and women in seven like sports. RESULTS: A total of 3,767 participants were included in the study, with 1874 sports-related injuries reported among the men and women's teams. Of these injuries, 856 (45.7%) were sustained by female and 1018 (54.3%) by male athletes. Overall, no statistically significant gender difference was found for injuries per 100 participant-years (52.5 for female athlete versus 47.7 for males). A statistically significant gender difference in injury incidence (p < 0.001) was seen for two sports: swimming and water polo. Female swimmers reported more back/neck, shoulder, hip, knee and foot injuries: and female water polo players reported more shoulder injuries. When evaluating all sports concurrently, female athletes reported a higher rate of hip, lower-leg and shoulder injuries, while male athletes reported a higher rate of thigh injuries. CONCLUSION: Except for some minor gender differences in total injuries for two sports and several differences in total injuries by anatomic location, our data suggest very little difference in the pattern of injury between men and women competing in comparable sports. The increased rate of shoulder injury among female swimmers probably resulted from the more rigorous training philosophy of their coach. Thus, no gender-specific recommendations can be suggested for decreasing the incidence of injury to female athletes competing in these sports.     

Physical fitness, cognitive performance, and aging

The relationship between physical fitness and cognitive performance in old age is examined in the light of contemporary capacity theories of attention. It is suggested that a model of cognition based upon the notion of a declining attentional capacity with advancing age provides a valuable conceptual framework for examining the influence of physical fitness on cognitive performance in old age. A direct prediction of the model is that cognitive tasks which require effortful processing should be more sensitive to the effects of fitness than tasks which can be performed without or with minimal attention. It is suggested that future research in the area of exercise and cognition systematically manipulate the attentional requirements of the tasks selected for the evaluation of cognitive performance. The implications of such a task-dependent association between physical fitness and cognitive performance for future research are discussed.     

Energy cost of physical task performance in men and women wearing chemical protective clothing

BACKGROUND: Chemical protective clothing (CPC) is required to perform certain occupations and is known to inhibit physical performance. Few data are available that quantify the physiological response of men and women during task performance while wearing CPC. HYPOTHESIS: The mobility of a task will have a significant effect on the change in energy cost. The energy cost of wearing CPC will be greater in women than men during physical task performance. METHODS: Energy cost (VO2) and the psychophysical scales, rating of perceived exertion (RPE) and respiratory distress (RD), were measured in 32 men and 26 women during the performance of 31 physical tasks. Tasks were categorized by mobility: stationary, intermittent or continuous. Between 6-12 men and 5-13 women conducted each task wearing 2 clothing conditions: battle-dress uniform (BDU, wt = 3.7 kg) and (CPC, wt = 9.3 kg). RESULTS: VO2 L x min(-1), was higher in CPC compared with BDU for the continuous task category for both genders. However, when VO2 (ml x kg(-1) clothed wt x min(-1)) was normalized for clothing weight, there remained a significant clothing effect for the continuous category, but there were no gender differences. VO2, expressed as a % VO2max, was significantly increased for BDU compared with CPC for the continuous task category only. This difference was significantly greater for women than men. Women exercised at a higher % VO2max and reported a higher RPE than men for all categories in both BDU and CPC. Both genders reported higher RD wearing CPC for the continuous task category only. CONCLUSIONS: There is an increase in energy cost wearing CPC during continuous tasks which can be attributed to both the clothing weight and the hobbling effect. Wearing CPC is more physiologically and psychologically demanding for women than men, especially when performing tasks of a continuous nature.     

Reliability of jumping performance in active men and women under different stretch loading conditions

BACKGROUND: To determine the reliability of squatting jumps (SJ), counter-movement jumps (CMJ) and drop jumps (DJ) tests, as well as the reliability of the optimal dropping height during drop jumping. METHODS: Jumping performance was assessed in 8 male and 9 female physical education students. Their age, weight and height (mean +/- SD) were 23.9 +/- 2.1 years, 72.0 +/- 12.1 kg, 174.3 +/- 10.4 cm, and 23.1 +/- 2.0 years, 54.8 +/- 4.9 kg, 160.1 +/- 5.0 cm for the males and females, respectively. The jumping performance was determined on six different testing days. On each testing day, squatting jumps (SJ) and counter-movement jumps (CMJ) were performed as well as drop jumps (DJ) from heights between 20 and 100 cm. The dropping height given the maximum attained height was registered as the optimal dropping height (ODH). After a 15 min rest period, a 30 sec hopping test (HT) was performed and the mean height attained (MHT) as well as the number of jumps executed (NHT) were recorded. The height attained was computed from the flight time, which was measured with a digital timer (+/- 0.001 sec) connected to a resistive platform. RESULTS: The pooled coefficients of variation in percentage were 5.4 (SJ), 6.3 (CMJ), 6.2 (DJ), 31.9 (ODH), 3.1 (NHT) and 6.7 (MHT). A parabolic relationship between dropping height and attained height was found (r = 0.39-0.43, p < 0.001). The ODH was 48.2 +/- 14.0 cm and 62.9 +/- 21.3 cm for females and males, respectively (p < 0.05). Multiple regression analysis showed than ODH can be predicted from the SJ with a standard error of 9 cm. CONCLUSIONS: The variability of the assessment of jumping performance is similar to that reported for other variables used in the assessment of physical fitness. In contrast, the assessment of the optimal dropping height is less reliable.