Effects of menthol application on the skin during prolonged immersion in cool and cold water.

The aim of the study was to compare the effect of skin surface menthol application on rectal temperature (Tre) during prolonged immersion in cool and cold water. We hypothesized that menthol application would lead to a slower Tre decline due to the reduced heat loss as a consequence of the menthol-induced vasoconstriction and that this effect would be attenuated during cold-water immersion. Six male subjects were immersed for 55 minutes in stirred cool (24°C) or cold (14°C) water immediately after attaining a Tre of 38°C by cycling at 60% of maximum heart rate on two occasions: without (ΝM) and with (M) whole-body skin application of menthol cream. Tre, the proximal-distal skin temperature gradient, and oxygen uptake were continuously measured. ANOVA with repeated measures was employed to detect differences among variables. Significance level was set at 0.05. The area under the curve for Tre was calculated and was greater in 24°C M (-1.81 ± 8.22 a.u) compared to 24°C NM (-27.09 ± 19.09 a.u., P = .03, r = .90), 14°C NM (-18.08 ± 10.85 a.u., P = .03, r = .90), and 14°C M (-11.71 ± 12.58 a.u, P = .05, r = .81). In cool water, oxygen uptake and local vasoconstriction were increased (P ≤ .05) by 39 ± 25% and 56 ± 37%, respectively, with menthol compared to ΝM, while no differences were observed in cold water. Menthol application on the skin before prolonged immersion reduces heat loss resulting in a blunted Tre decline. However, such a response is less obvious at 14°C water immersion, possibly because high-threshold cold-sensitive fibers are already maximally recruited and the majority of cold receptors saturated.

The effect of foot overpronation on Achilles tendon blood supply in healthy male subjects.

The purpose of this study was to investigate Achilles tendon blood flow in individuals with overpronated feet during non-weight- and weight-bearing positions. Achilles tendon blood flow was measured by means of the pulsatility index (PI) and the resistance index (RI) in 15 male individuals with overpronated feet and 15 counterparts with normal feet, using power Doppler ultrasonography (PDI). Achilles tendon ultrasonographic (US) assessment was performed at its musculo-tendinous junction (MTJ), mid-tendon (MT), and osseotendinous junction (OTJ) at a non-weight-bearing relaxed position (RP) and during two-leg stance (TLS) and one-leg upright stance (OLS). PI and RI indices were significantly greater in individuals with overpronated feet compared to individuals with normal feet at the OTJ in OLS position (P < 0.01), and at MT in both TLS (P < 0.001) and OLS positions (P < 0.001). All individuals demonstrated also greater PI and RI indices at MT followed by the OTJ and MTJ in all positions (P < 0.001), and in OLS compared to TLS and the RP at the OTJ (P < 0.01) as well as at MT and MTJ (P < 0.001). The findings of the present study suggest that foot overpronation may affect Achilles tendon blood flow, particularly at mid-tendon, thus enhancing the possibility for injury.

Effects of menthol application on the skin during prolonged immersion in swimmers and controls.

We hypothesized that menthol application on the skin would enhance vasoconstriction of subjects immersed in cool water, which would reduce heat loss and rectal temperature (Tre) cooling rate. Furthermore, it was hypothesized that this effect would be greater in individuals acclimatized to immersion in 24 °C water, such as swimmers. Seven swimmers (SW) and seven physical education students (CON) cycled at 60% VO2 max until Tre attained 38 °C, and were then immediately immersed in stirred water maintained at 24 °C on two occasions: without (NM) and with (M; 4.6 g per 100 mL of water) whole-body skin application of menthol cream. Heart rate, Tre, proximal-distal skin temperature gradient, oxygen uptake (VO2 ), electromyographic activity (EMG), and thermal sensation were measured. Tre reduction was similar among SW and CON in NM and CON in M (-0.71±0.31 °C in average), while it was smaller for SW in M (-0.37±0.18 °C, P < 0.01). VO2 and heart rate were greater in M compared with NM condition (P = 0.01). SW in M exhibited a shift of the threshold for shivering, as reflected in increased VO2 and EMG activity, toward a higher Tre compared with the other trials. Menthol application on the skin before immersion reduces heat loss, but defends Tre decline more effectively in swimmers than in non-swimmers.

Heritability of the rate of torque development.

AIM: The aim of this study was to estimate the genetic and environmental contribution to the variation observed in the rate of torque development (RTD), which is considered an important determinant of sport performance. METHODS: Nine monozygotic (MZ) and seven dizygotic (DZ) twin pairs, of both sexes aged 19-26 years, performed three isometric maximal voluntary contractions with the knee at 70 degrees and 40 degrees of flexion (0 degrees=terminal extension) on a Contrex Isokinetic dynamometer. The RTD was extracted from the force time curves and calculated in two different ways, giving rise to two indices, the maximal rate of torque development (MRTD), and the torque at the first 100 msec (F100msec). Heritability estimates (h2) were derived on the basis of intrapair variances between MZ and DZ twin pairs. RESULTS: A significant genetic influence (P<0.05) was found for both RTD indices (h2=0.99, and 0.93 for MRTD, and F100msec respectively) at only 40 degrees of knee flexion, an angle associated with intensive neural activation. CONCLUSION: The maximal rate of torque development of knee extensor muscles during the initial phase of their contraction and at enhanced neural activation, is under strong genetic influence.

Reduced metaboreflex control of blood pressure during exercise in individuals with intellectual disability: a possible contributor to exercise intolerance.

The aim was to investigate the hemodynamic responses to isometric handgrip exercise (HG) and examine the role of the muscle metaboreflex in the exercise pressor response in individuals with intellectual disability (IID) and non-disabled control subjects. Eleven males with mild-moderate intellectual disabilities and eleven non-disabled males performed a testing protocol involving 3-min periods of baseline, HG exercise (at 30% MVC), circulatory occlusion, and recovery. The same protocol was repeated without occlusion. At baseline, no differences were detected between groups in beat-to-beat mean arterial pressure (MAP), heart rate (HR), stroke volume, and peripheral resistance. IID were able to sustain an exercise MAP response at comparable levels to the control group exerting similar peripheral resistance; however, IID exhibited a blunted chronotropic response to HG and a diminished exercise vagal withdrawal compared to controls. During occlusion, IID exhibited a lower pressor response than their control peers, associated with a lower increase in peripheral resistance during this task. In conclusion, although intellectual disabilities can be the consequence of many different genes, IID share common deficits in the chronotropic response to exercise and a blunted metaboreflex-induced pressor response.

Role of cardiorespiratory fitness and obesity on hemodynamic responses in children.

AIM: The purpose of this study was to examine the effects of cardiorespiratory fitness (CRF) and obesity on arterial blood pressure and its determinants at rest and during isometric handgrip exercise (IHG) in children. METHODS: Fourty-eight healthy children aged 11.6±0.3 (mean ±SE) years, (24 obese or overweight [OB/OV]; 24 normal weight [NO]) participated in the study. Both groups were divided into fit or unfit subgroups according to children's performance of an exercise test (PWC170). Arterial pressure and its determinants were recorded with the use of a photoplethysmographic device (FINOMETER) during 5 minutes of rest and 3 minutes of IHG at 30% of maximum voluntary contraction. RESULTS: At rest and during IHG, unfit OB/OV children had higher systolic, mean arterial pressure, and rate pressure product (P≤0.05) than fit OB/OV children whose responses were similar to NO children, fit or unfit. Changes from rest, in cardiac output, cardiac index, and stroke volume were higher in unfit than in fit OB/OV children (P≤0.05). Unfit OB/OV children exceeded their fit counterparts in several anthropometric measures. However, CRF was found to have a main effect on systolic blood pressure (P=0.05). CONCLUSION: Unfit versus fit OB/OV children had an exaggerated systolic blood pressure response at rest and during sympathetic activation, presumably coupled with higher cardiac output and cardiac oxygen demand. These results highlight the importance of fitness for health maintenance in obese and overweight children.

Importance of characteristics and modalities of physical activity and exercise in defining the benefits to cardiovascular health within the general population: recommendations from the EACPR (Part I).

Over the last decades, more and more evidence is accumulated that physical activity (PA) and exercise interventions are essential components in primary and secondary prevention for cardiovascular disease. However, it is less clear whether and which type of PA and exercise intervention (aerobic exercise, dynamic resistive exercise, or both) or characteristic of exercise (frequency, intensity, time or duration, and volume) would yield more benefit in achieving cardiovascular health. The present paper, as the first of a series of three, will make specific recommendations on the importance of these characteristics for cardiovascular health in the population at large. The guidance offered in this series of papers is aimed at medical doctors, health practitioners, kinesiologists, physiotherapists and exercise physiologists, politicians, public health policy makers, and the individual member of the public. Based on previous and the current literature, recommendations from the European Association on Cardiovascular Prevention and Rehabilitation are formulated regarding type, volume, and intensity of PA and exercise.

Importance of characteristics and modalities of physical activity and exercise in the management of cardiovascular health in individuals with cardiovascular risk factors: recommendations from the EACPR. Part II.

In a previous paper, as the first of a series of three on the importance of characteristics and modalities of physical activity (PA) and exercise in the management of cardiovascular health within the general population, we concluded that, in the population at large, PA and aerobic exercise capacity clearly are inversely associated with increased cardiovascular disease risk and all-cause and cardiovascular mortality and that a dose­response curve on cardiovascular outcome has been demonstrated in most studies. More and more evidence is accumulated that engaging in regular PA and exercise interventions are essential components for reducing the severity of cardiovascular risk factors, such as obesity and abdominal fat, high BP, metabolic risk factors, and systemic inflammation. However, it is less clear whether and which type of PA and exercise intervention (aerobic exercise, dynamic resistive exercise, or both) or characteristic of exercise (frequency, intensity, time or duration, and volume) would yield more benefit for each separate risk factor. The present paper, therefore, will review and make recommendations for PA and exercise training in the management of cardiovascular health in individuals with cardiovascular risk factors. The guidance offered in this series of papers is aimed at medical doctors, health practitioners, kinesiologists, physiotherapists and exercise physiologists, politicians, public health policy makers, and individual members of the public. Based on previous and the current literature overviews, recommendations from the European Association on Cardiovascular Prevention and Rehabilitation are formulated regarding type, volume, and intensity of PA and regarding appropriate risk evaluation during exercise in individuals with cardiovascular risk factors.

Altered hemodynamic regulation and reflex control during exercise and recovery in obese boys.

The aims of the present study were to assess in obese and lean boys 1) the hemodynamic responses and baroreflex sensitivity (BRS) to isometric handgrip exercise (HG) and recovery and 2) the muscle metaboreflex-induced blood pressure response and the variables that determine this response. Twenty-seven boys (14 obese and 13 lean boys, body mass index: 29.2 ± 0.9 vs. 18.9 ± 0.3 kg/m(2), respectively) participated. The testing protocol involved 3 min of baseline, 3 min of HG (30% maximum voluntary contraction), 3 min of circulatory occlusion, and 3 min of recovery. The same protocol was repeated without occlusion. At baseline, no differences were detected between groups in beat-to-beat arterial pressure (AP), heart rate (HR), and BRS; however, obese boys had higher stroke volume and lower total peripheral resistance than lean boys (P < 0.05). During HG, lean boys exhibited higher HR and lower BRS compared with their obese counterparts. In lean boys, BRS decreased during HG compared with baseline, whereas in obese boys, it was not significantly modified. In lean boys, TPR was elevated during HG and declined after exercise, whereas in obese boys, TPR did not significantly decrease after exercise cessation. In the postexercise period, BRS in lean boys returned to baseline, whereas an overshoot was observed in obese boys. Postexercise BRS was correlated with body mass index (R = 0.56, P < 0.05). Although the metaboreflex-induced increase in AP was similar between obese and lean children, it was achieved via different mechanisms: in lean children, total peripheral resistance was the main contributor to AP maintenance during the metaboreflex, whereas in obese children, stroke volume significantly contributed to AP maintenance during the metaboreflex. In conclusion, obese normotensive children demonstrated altered cardiovascular hemodynamics and reflex control during exercise and recovery.

The role of pulse transit time as an index of arterial stiffness during exercise.

The aim of the present study was to investigate, whether pulse transit time (PTT), a popular index of arterial stiffness at rest, can be also used as such, during steady state exercise. For this purpose, twelve male volunteers exercised on a cycle ergometer for 70 min on three separate occasions whereas, cycling cadence and workload were manipulated in order to produce diverse cardiorespiratory responses. PTT, blood pressure, cardiac output and respiratory frequency were measured during exercise. Resistance to systole and total peripheral resistance were calculated by the ratio of systolic pressure, and mean arterial pressure over cardiac output, respectively. All subjects across all conditions, showed a negative linear correlation (P < 0.01) between changes in PTT and systolic pressure (SP) (r = -0.66), changes in cardiac output (r = -0.76), and respiratory frequency (r = -0.40), whereas PTT was positively correlated (P < 0.05) with total peripheral resistance (r = 0.31), the SP to cardiac output ratio (r = 0.30) and plasma volume changes (r = 0.29). However, forward stepwise multiple regression analysis revealed that 71% (P < 0.001) of PTT changes from rest (DeltaPTT) variability was attributed to changes in cardiac output, SP and SP to cardiac output ratio. In the same model, total peripheral resistance did not exert significant influence on DeltaPTT variability. In conclusion, PTT is a reflection not only of SP but also of cardiac output changes per se and in combination with cardiac output (SP to cardiac output ratio) and should not be used as a pure marker of arterial stiffness under marked exercise cardiovascular and respiratory perturbations.

Quadriceps oxygenation during isometric exercise in sailing.

The aim of the present study was to investigate why blood lactate after prolonged quadriceps contraction during hiking is only marginally increased. Eight sailors performed five 3-min hiking bouts interspersed with 5-s recovery periods. Whole body oxygen uptake, heart rate and lactate were recorded, along with continuous-wave near-infrared spectroscopy measures of quadriceps oxygenation. The time for 50% re-oxygenation was also assessed as an indication of the degree of localized oxygen delivery stress. Hiking elicited a significant (p = 0.001) increase in mean (+/- SD) heart rate (124 +/- 10 beats . min (-1)) which was accompanied by a disproportionately low oxygen uptake (12 +/- 2 ml.kg(-1).min(-1)). Lactate was significantly (p = 0.001) increased throughout hiking manoeuvres, though post-exercise it remained low (3.2 +/- 0.9 mmol.l(-1)). During the hiking bouts mean quadriceps oxygenation was significantly (p = 0.001) reduced compared to baseline (by 33 +/- 5%), indicating an imbalance between muscle oxygen accessibility and oxygen demand. During rest intervals quadriceps oxygenation was partially restored. After the end of the final bout the time for 50 % re-oxygenation was only 8 +/- 2 s, whereas recovery of quadriceps oxygenation and oxygen uptake was completed within 3 min. We conclude that the observed low lactate could be attributed to the small oxygen and energy deficits during hiking as the muscles' oxygen accessibility is presumably partially restored during the brief rest intervals.

Genetic variation of maximal velocity and EMG activity.

There is a scarcity of studies on genetic variation of essential components of neuromuscular performance, such as maximal velocity and EMG activity during maximal effort. Using the twin model and comparing intrapair differences between monozygotic (MZ) and dizygotic (DZ) twins, we derived for these neuromuscular components heritability estimates (h2), signifying the phenotypic variance due to genetic differences. A group of forty healthy male twins, 10 MZ and 10 DZ pairs, aged 21.5 +/- 2.4 and 21.0 +/- 2.1 yr, respectively, performed dynamic elbow flexion to assess maximal velocity, and maximal isometric contraction to assess EMG activity of the biceps brachii muscle. Intrapair differences for maximal velocity in MZ and DZ twins were 0.22+/- 0.04 and 0.55 +/- 0.17 m x s(-1), and intrapair correlations were 0.95 and 0.54, respectively; h2 for maximal velocity was 0.84. Likewise, intrapair differences for EMG activity during maximal isometric contraction were 0.061 +/- 0.03 in MZ and 0.176 mV in DZ; the respective intrapair correlations were 0.93 and 0.46, and h2 was 0.85. In conclusion, maximal velocity of the upper limb, using a simple movement of a single joint and EMG activity during maximal isometric contraction, seems to be highly heritable characteristics in humans.

Anaerobic capacity, isometric endurance, and Laser sailing performance.

Laser sailors have to tolerate fatiguing contractions of the lower-body muscles for prolonged periods. The aims of the present study were (1) to evaluate the difference between top-ranked and club sailors, in their capacity to resist fatigue during sustained isometric and maximal power exercise, and (2) to examine the relationships between the above parameters and performance on a Laser simulator and competitive racing performance according to the national ranking list. Eight Greek nationally ranked Laser sailors were compared with eight club sailors. Each sailor performed: (a) an effort to the limit of tolerance on the Laser simulator, (b) an effort to the limit of tolerance of isometric endurance for the right leg on an isokinetic dynamometer, and (c) a Wingate test of maximal lower-body anaerobic power on a cycle ergometer. In the nationally ranked sailors, isometric endurance time (mean 160 s, s = 50) and endurance time on the Laser simulator (1381 s, s = 1354) were significantly (P < 0.05) longer than in the club sailors (101 s, s = 29 and 565 s, s = 367, respectively), whereas the final minute heart rate (in both groups: 149 beats . min(-1), s = 22) and the mean arterial pressure (nationally ranked sailors: 129 mmHg, s = 16; club sailors: 120 mmHg, s = 21) on the Laser simulator were not different between groups. During the Wingate test, the nationally ranked sailors had a significantly lower index of fatigue (42%, s = 5) than the club sailors (49%, s = 6). Isometric endurance time was significantly correlated with the Wingate index of fatigue (r = -0.73; P < 0.001). The nationally ranked sailors' mean and maximal anaerobic powers were significantly correlated with their national ranking positions (r = -0.83 and -0.71, respectively). It is suggested that isometric endurance and anaerobic power are well-developed in Laser class sailors and may influence their sailing performance. Furthermore, compared with club sailors, the nationally ranked sailors are able to sustain the same intensity of lower-limb isometric contractions for much longer with similar cardiovascular responses.

The influence of game duration and playing position on intensity of exercise during match-play in elite water polo players.

In this study, we assessed exercise intensity in 20 water polo games of different duration. The hypothesis that right wing players perform at a higher intensity than back and forward central players was also tested. Thirty water polo players, equally split between three field positions, participated in the study. Initially, their performance-related physiological capabilities were evaluated. Subsequently, during water polo games of short (4 x 7-min periods) or long duration (4 x 9-min periods), heart rate was monitored continuously and blood lactate concentration was measured at the end of each period. Activity patterns were also recorded using a video camera. Mean heart rate over the entire game was 156 +/- 18 beats x min(-1). Overall exercise intensity fluctuated around a value corresponding to the lactate threshold (4.03 +/- 0.96 mmol x l(-1), 86 +/- 5% of peak heart rate) and decreased (P < 0.003) with game time (4.22 +/- 1.8 and 3.47 +/- 1.9 mmol x l(-1) in the second and fourth quarter, respectively). During the last 6 min, heart rate was higher (P < 0.001) in games of short duration (156 +/- 3 beats x min(-1)) than in games of long duration (152 +/- 8 beats x min(-1)). Video analysis showed that the percentage of time spent in low-intensity activities (i.e. "out of game") was lower (23 vs. 26%), whereas that in high-intensity activities (i.e. "sprinting crawl") was higher (21 vs. 19%), in games of short compared with long duration. No difference was observed among players of various field positions in any of the variables examined. Thus during match-play, games of long duration produced significantly lower heart rate responses than games of short duration, and the physiological response exhibited by the players was not affected by field position. The water polo authorities should consider these results before changing game duration and coaches should prepare their athletes accordingly.

Patterns of dynamic hyperinflation during exercise and recovery in patients with severe chronic obstructive pulmonary disease.

BACKGROUND: Not all patients with severe chronic obstructive pulmonary disease (COPD) progressively hyperinflate during symptom limited exercise. The pattern of change in chest wall volumes (Vcw) was investigated in patients with severe COPD who progressively hyperinflate during exercise and those who do not. METHODS: Twenty patients with forced expiratory volume in 1 second (FEV(1)) 35 (2)% predicted were studied during a ramp incremental cycling test to the limit of tolerance (Wpeak). Changes in Vcw at the end of expiration (EEVcw), end of inspiration (EIVcw), and at total lung capacity (TLCVcw) were computed by optoelectronic plethysmography (OEP) during exercise and recovery. RESULTS: Two significantly different patterns of change in EEVcw were observed during exercise. Twelve patients had a progressive significant increase in EEVcw during exercise (early hyperinflators, EH) amounting to 750 (90) ml at Wpeak. In contrast, in all eight remaining patients EEVcw remained unchanged up to 66% Wpeak but increased significantly by 210 (80) ml at Wpeak (late hyperinflators, LH). Although at the limit of tolerance the increase in EEVcw was significantly greater in EH, both groups reached similar Wpeak and breathed with a tidal EIVcw that closely approached TLCVcw (EIVcw/TLCVcw 93 (1)% and 93 (3)%, respectively). EEVcw was increased by 254 (130) ml above baseline 3 minutes after exercise only in EH. CONCLUSIONS: Patients with severe COPD exhibit two patterns during exercise: early and late hyperinflation. In those who hyperinflate early, it may take several minutes before the hyperinflation is fully reversed after termination of exercise.

Somatic and physical traits affecting sprint swimming performance in young swimmers.

The aim of this study was to examine the relationship between anthropometry, physical capacity, and sprint swimming performance in swimmers of both genders aged 12 - 14 years old. Anthropometric characteristics (body height and mass, total upper extremity, hand and foot lengths, chest circumference, certain body breadths, and skinfolds), as well as leg explosiveness (horizontal jump) and arm strength (handgrip strength test) were evaluated in 263 competitive swimmers (178 boys and 85 girls) aged 12 - 14 years. Skeletal age was assessed with the Tanner-Whitehouse method. All variables, except for the ankle and shoulder flexibility as well as the skeletal age, correlated with 100 m freestyle performance in boys (r = - 0.46 to - 0.73, p < 0.01). Using a split-sample approach, upper extremity length, horizontal jump, and grip strength were detected as significant predictors of 100 m freestyle performance in boys (R (2) = 0.59, p < 0.01). In girls, body height, upper extremity and hand length, shoulder flexibility, and horizontal jump were all significantly related to 100 m freestyle time (r = - 0.22 to - 0.31, p < 0.05) but the degree of association was markedly lower than in boys. In addition, only 17 % of the variance in performance was explained by a combination of body height, hand length, and horizontal jump in girls. These results suggest that 100 m freestyle performance can be partially explained by anthropometry and physical capacity tests in young swimmers. The contribution of these factors to sprint swimming performance is different in boys and girls and this requires further research. These findings could be used for male young swimmers' selection.

Physiological and technical characteristics of elite young basketball players.

AIM: The aim of this study was 2-fold: a) to describe the physiological and technical characteristics of elite young basketball players, and b) to examine the relationship between certain field and laboratory tests among these players. METHODS: Thirteen male players of the junior's Basketball National team (age: 18.5 +/- 0.5 years, mass: 95.5 +/- 8.8 kg, height: 199.5 +/- 6.2 cm, body fat: 11.4 +/- 1.9%, means+/-SD) performed a run to exhaustion on the treadmill, the Wingate test and 2 types of vertical jump. On a separate day, the field tests (control dribble, defensive movement, speed dribble, speed running, shuttle run and dribble shuttle run) were conducted. RESULTS: Maximal oxygen uptake (VO2max) and ventilatory threshold were 51.7 +/- 4.8 ml/kg/min and 77.6 +/- 7.0% VO2max, respectively. Maximum power output was 10.7 +/- 1.3 Watts/kg and mean power (Pmean) 8.0 +/- 0.7 Watts/kg. Counter-movement and squat jump height were 40.1 +/- 3.7 and 39.8 +/- 4.0 cm, respectively. Performance in control dribble (13.70 +/- 0.96 s), speed dribble (4.24 +/- 0.75 s), high intensity shuttle run (27.90 +/- 1.04 s) and dribble shuttle run (29.50 +/- 1.22 s) was correlated with Pmean (r=-0.58, r=-0.62, r=-0.56 and r=-0.73, respectively, p<0.05). Percent body fat was negatively correlated with all the above field tests (r=0.63, r=0.57, r=0.66, r=0.65, respectively, p<0.05). CONCLUSION: These players presented a moderate VO2max and anaerobic power. The significant correlation between Pmean and certain field tests indicates that these tests could be used for the assessment of anaerobic capacity of young basketball players.

Age-related pattern in body composition changes for 18-69 year old women.

AIM: The aim of this study was to describe the age-related pattern in body composition changes for women 18-69 years old. A secondary objective was to assess the relationship between accumulated physical activity and body composition. METHODS: Anthropometric measures, including height, body mass, waist and hip circumference and skinfolds thickness, were taken from 441 healthy women placed in 5 age groups (group 1: 18-29 years, n=71; group 2: 30-39 years, n=69; group 3: 40-49 years, n=159; group 4: 50-59 years, n=92 and group 5: 60-69 years, n=50). Physical activity was assessed with a questionnaire. A 1-way ANOVA, with group 1 as the control and Pearson correlation coefficient were employed for statistical analysis. RESULTS: Body Mass Index, fat mass and waist to hip ratio were all higher in the age groups of 40-49 years and above (21.8+/-0.4 kg/m(2), 14.7+/-0.6 kg, 0.73+/-0.01 for age group 18-29 years and 24.7+/-0.3 kg/m(2), 20.8+/-0.4 kg and 0.76+/-0.01 for age group 40-49 years, respectively; means+/-S.E.M; p<0.01 for all variables). In contrast, fat free mass remained unchanged in the age spectrum studied. Central adiposity, as indicated by the trunk to extremity skinfold ratio, increased after 50-59 years compared with the 18-29 years old group (p<0.01). Body fatness and central adiposity were associated with aging (r=0.16 to 0.46, p<0.05), but not with accumulated physical activity. CONCLUSION: The results of this cross-sectional study showed an age-related increase in body fatness and central adiposity with no detectable change in fat free mass in these women. These changes were not associated with physical activity.

Effect of cold air inhalation on core temperature in exercising subjects under heat stress.

Whether increasing respiratory heat loss (RHL) during exercise under heat stress can contain elevation of rectal temperature (Tre) was examined. Eight men cycled twice at 45-50% their maximum work rate until exhaustion at ambient temperature and relative humidity of 38 degrees C and 90-95%, respectively. They inspired either cold (3.6 degrees C) or ambient air in random sequence. When subjects breathed cold air during 23 min of exercise, a ninefold increase in RHL was observed vs. similar work during hot air inhalation (32.81 vs. 3.46 W). Respiratory frequency (f) and rate of rise in Tre decreased significantly (P less than or equal to 0.004 and P less than or equal to 0.002, respectively). The rise in skin temperature in each inhalant gas condition was accompanied by a parallel almost equal increase in core temperature above basal (delta Tre) for equivalent gains in skin temperature. The increase in tidal volume and decreased f in the cold condition allowed more effective physical conditioning of cold inspirate gas in the upper airways and aided RHL. Cold air inhalation also produced a significant (P less than or equal to 0.05) decrease in heart rate vs. hot air inhalation in the final stages of exercise. Insignificant changes in O2 consumption and total body fluid loss were found. These data show that cold air inhalation during exercise diminishes elevation of Tre and suggest that both the intensity and duration of work can thus be extended. The importance of the physical exchange of heat energy and any physiological mechanisms induced by the cold inspirate in producing the changes is undetermined.