Effects of age on ventilatory threshold and peak oxygen uptake normalised for regional skeletal muscle mass in Japanese men and women aged 20–80 years

Ventilatory threshold (VT) is an important predictor of cardiorespiratory fitness, such as peak oxygen uptake (VO2peak) and is a valuable index of aerobic exercise intensity. However, little is known about the role of skeletal muscle (SM) mass in the age-associated decline of VT. Therefore, the present study was performed to investigate the effects of age on cardiopulmonary fitness normalised for regional SM mass in 1,463 Japanese men and women, and to determine the relevance of VT normalised to SM mass based on age and gender. Total, trunk and thigh SM mass were measured using an ultrasound method, while VO2peak and VT were determined during treadmill walking. VO2peak was estimated using the predicted maximum heart rate (HR) and the HR-VO2 relationship for sub-maximal treadmill walking. There were significant negative correlations between VT normalised for body mass and age in men and women (P < 0.001). Age-associated declines were also observed in VT normalised for body mass in both men and women; however, VT normalised for SM mass was not significantly different with age. Significant correlations were also observed between thigh SM mass and VT in both men and women. These results suggest that thigh SM mass is closely associated with VO2peak and/or VT in both men and women, and the decrease in VT with age is predominantly due to an age-related decline of SM mass. Moreover, this study provides normative cardiorespiratory fitness data regarding VT normalised SM mass in healthy men and women aged 20-80 years.     

Estimation of maximal heart rate using the relationship between heart rate variability and exercise intensity in 40–67 years old men

Large interindividual variation in maximal heart rate (HR_max) may not be accounted for by age alone. In order to evaluate a novel method in the prediction of HR_max, this study examined the profile of HR variability (HRV) during exercise in 40–67 years old men (n = 74). R–R intervals were recorded during supine rest and during a graded exercise test by cycle ergometry until exhaustion. A third-degree polynomial function was fitted to the HRV data recorded during exercise to represent the HRV profile of each subject. The instantaneous beat-to-beat R–R interval variability (SD1), high (HF) and low frequency power decreased between all consecutive exercise intensities (P < 0.033). The relationship between HR_max and a variable illustrating the declining rate of HF (HR_HF50%) was stronger (r = 0.50, P < 0.001) than between HR_max and age (r = −0.36, P < 0.01). The regression analysis showed that a more accurate estimation of HR_max was attained when HRV was used in the equation in addition to age: HR_max = 160.633–0.603(age) + 0.441(HR_HF50%) (SEE = 9.8 bpm vs. 11.6 bpm in the equation based on age alone). The decline of HRV during incremental exercise seems to be useful for accurate estimation of maximal heart rate.     

Muscular strength and aerobic capacity in men 50–64 years old

Summary 44 men 50–54 years old, 22 men 55–59 and 5 men 60–64 years old were examined with regard to maximal isometric strength of the elbow flexors and lifting strength.The mean value of the muscular strength of the elbow flexors was for the first age group 25 kp, for the second 26 and for the third 21 kp. The corresponding values for the lifting strength were 145,141 and 123 kp respectively.The correlation between muscular strength and aerobic work capacity was low.     

Epididymo-orchitis caused by enteric organisms in men &gt; 35 years old: beyond fluoroquinolones

Epididymo-orchitis is a common urological condition in men of all ages, causing a unilateral or bilateral swelling of the epididymis and/or testis. It is frequently caused by sexually transmitted infections, Chlamydia trachomatis and Neisseria gonorrheae, as well as common enteric organisms implicated in urinary tract infections. Men over 35 years old may develop epididymo-orchitis associated with enteric organisms, often associated with functional bladder outlet problems such as benign prostatic hyperplasia or urethral stricture disease. Fluoroquinolones, especially ciprofloxacin, have long been the mainstay of treatment for these infections; however, rising resistance to ciprofloxacin in E. coli isolates in Europe and the USA means that there is an unprecedented necessity for alternative antimicrobials with adequate penetration into genital tissues (epididymis and testes) to allow appropriate and comprehensive treatment of epididymo-orchitis in this group of patients.     

Determinants of vitamin D status in healthy men and women aged 40–80 years

ObjectivesTo determine the contribution of life style and health related factors on vitamin D status in middle-aged and older men and women.Study designA cross-sectional single-center study in 400 male subjects (40–80 years) and 402 postmenopausal female subjects (56–73 years), conducted in a University Medical Center in the central part of the Netherlands (52 degrees northern latitude).Main outcome measuresMedical history, vitamin D, calcium and alcohol intake, physical activity, Body Mass Index, Blood pressure, smoking, total fat body mass and total lean body mass were measured using DEXA. Laboratory analysis included 25-hydroxyvitamin D (25OHD) and sex hormones.ResultsThirty-six percent of men and 51% of women had 25OHD less than 50 nmol/L. In summertime men had significant higher 25OHD as compared to women (81.5 vs 53.3 nmol/L, P = .000) but this difference disappeared come winter. In a saturated model, male gender (B = .16, P = .008), and season (summer vs winter B = .30, P = .000) remained statistically significant. In men, physical activity and season explained 21% of the variance. In women, household physical activity (B = .13, P = .03), sport physical activity (B = .02, P = .02) and estradiol (B = ?.003, P = .048) remained in the model,.ConclusionIn healthy middle-aged and older men and postmenopausal women, male gender and season were important predictors of vitamin D status. In men, physically activity and season, explained 21% of the variance in vitamin D status. In women, physical activity and estradiol explained 9.3% of the variance in vitamin D.     

Quadriceps maximal power and optimal shortening velocity in 335 men aged 23–88 years

The ability to develop adequate quadriceps muscle power may be highly predictive of subsequent disability among older persons. Rate as well as quantitative (sarcopenia) and qualitative (among other slowing of muscles) contributors to that age-related power decline are poorly known. The relationship of quadriceps maximal short-term power (P_max) and corresponding optimal shortening velocity (_opt) with age was assessed in 335 healthy men aged 23–88 years. The P_max and _opt were measured on a friction loaded non-isokinetic cycle ergometer. Anthropometric dimensions were used to estimate lean thigh volume (LTVest) and quadriceps mass. The decline in P_max across the adult life span (10.7% per decade) was greater than the usually reported decrease in maximal muscle strength. Power decreased already after the fourth decade. Both muscle mass (4.1% decline for LTVest or 3.4% for quadriceps mass per decade) and _opt (6.6% decline per decade) contributed to the decrease in power. Age contributed to the variability in P_max independently to the LTVest/quadriceps mass and _opt. The age-related decrease pattern of P_max reflects both stabilization (or even increase) of anthropometric measures (LTVest or quadriceps mass) from youth to middleage and systematic decline of _opt already from the thirties. This implicates more focus on velocity-orientated training as a means of enhancing leg power and improving functional status.     

Daily physical activity and its relation to aerobic fitness in children aged 8–11 years

A positive relationship between daily physical activity and aerobic fitness exists in adults. Studies in children have given conflicting results, possibly because of differences in methods used to assess daily physical activity and fitness. No study regarding daily physical activity and fitness in children has been published, where fitness has been assessed by direct measurement of maximum oxygen uptake and related to daily physical activity intensities by accelerometers. We examined 248 children (140 boys and 108 girls), aged 7.9–11.1 years. Maximum workload and maximal oxygen uptake (VO_2PEAK) by indirect calorimetry were measured during a maximum bicycle ergometer exercise test. Exercise capacity was adjusted for body mass and (body mass)^2/3. Daily physical activity was evaluated by accelerometers, worn around the waist for 4 days. Mean accelerometer counts and time spent in vigorous physical activity were calculated. VO_2PEAK was correlated with mean accelerometer counts (r=0.23 for boys and r=0.23 for girls, both P<0.05), but somewhat better with time spent in vigorous activity (r=0.32 for boys, r=0.30 for girls, both P<0.05). All results remained virtually the same regardless of the method used to adjust for differences in body size.     

Indices of electromyographic activity and the “slow” component of oxygen uptake kinetics during high-intensity knee-extension exercise in humans

The control of pulmonary oxygen uptake kinetics above the lactate threshold (LT) is complex and controversial. Above LT, for square-wave exercise is greater than predicted from the sub-LT –WR relationship, reflecting the contribution of an additional “slow” component Investigators have argued for a contribution to this slow component from the recruitment of fast-twitch muscle fibres, which are less aerobically efficient than slow-twitch fibres. Six healthy subjects performed a rapid-incremental bilateral knee-extension exercise test to the limit of tolerance for the estimation of ventilatory threshold (VT), and the difference between and at VT (Δ). Subjects then completed three repetitions of square-wave exercise at 30% of VT for 10 min (moderate intensity), and at VT + 25%Δ (heavy intensity) for 20 min. Pulmonary gas exchange was measured breath-by-breath. Surface EMG was recorded from m. rectus femoris; integrated EMG (IEMG) and mean power frequency (MPF) were derived for successive contractions. In comparison to moderate-intensity exercise, the phase 2 kinetics in heavy exercise were marginally slower than for moderate-intensity exercise (time constant (± SD) 25 ± 9 and 22 ± 10 s, respectively; NS), with a discernible ( difference between minutes 6 and 3 of exercise: 74 ± 21 and 0 ± 20 ml min⁻¹, respectively). However, there was no significant change in IEMG or MPF, either in the moderate domain or in the heavy domain over the period when the slow component was manifest. These observations argue against an appreciable preferential recruitment of fast-twitch units with high force-generating characteristics and fast sarcolemmal conduction velocities in concert with the development of the slow component during heavy-intensity knee-extensor exercise. The underlying mechanism(s) remains to be resolved.     

Coping with unfair treatment at work--what is the relationship between coping and hypertension in middle-aged men and Women? An epidemiological study of working men and women in Stockholm (the WOLF study)

BACKGROUND: An important hypothesis in psychosomatic medicine is that exposure to psychosocial factors that arouse anger may accelerate the onset of hypertension, particularly if the subject is not allowed to show anger or to deal constructively with the factor that evoked it. For working men and women, being treated in an unfair way at work may be crucial. The present study was designed to answer the question whether the pattern of coping - primarily directed towards the aggressor (open) or directed inwards or towards others (covert) - is associated with hypertension among working men and women. STUDY GROUP: Five thousand seven hundred and twenty working men and women aged 15-64 participated in the study. The participation rate was 76%. METHODS: The coping pattern was studied by means of a Swedish version of a self-administered questionnaire that was originally introduced by Harburg et al. RESULTS: Significant results were confined to the age group 45-54. All analyses were adjusted for age and body mass index. Smoking habits and social class had no effect on the relationships. Low scores (lowest quartile) for open coping tended to be associated with an elevated prevalence ratio (PR) of hypertension both among men (PR 1.3, 95% confidence interval, CI, 0.9-1.7) and women (PR 1.4, 95% CI 1.0-2.0). High scores for covert coping (highest quartile) were associated with an elevated PR of hypertension among men (PR 1.6, 95% CI 1.2-2.2) but not in women. If the analysis was confined to cases without medication, the relationship between a high level of covert coping and high blood pressure was still significant for men. For women, however, no significant findings were made after this operation. Accordingly, the relationship between a low level of open coping and hypertension in women was confined to women with medication. Coping patterns were correlated with psychosocial work environment factors, in particular decision latitude. CONCLUSION: In men, covert coping was associated with prevalence of hypertension. In women, there tended to be a relationship between low scores for open coping and hypertension.     

70 μM caffeine treatment enhances in vitro force and power output during cyclic activities in mouse extensor digitorum longus muscle

Caffeine ingestion by human athletes has been found to improve endurance performance primarily acting via the central nervous system as an adenosine receptor antagonist. However, a few studies have implied that the resultant micromolar levels of caffeine in blood plasma (70 M maximum for humans) may directly affect skeletal muscle causing enhanced force production. In the present study, the effects of 70 M caffeine on force and power output in isolated mouse extensor digitorum longus muscle were investigated in vitro at 35°C. Muscle preparations were subjected to cyclical sinusoidal length changes with electrical stimulation conditions optimised to produce maximal work. 70 M caffeine caused a small but significant increase (2–3%) in peak force and net work produced during work loops (where net work represents the work input required to lengthen the muscle subtracted from the work produced during shortening). However, these micromolar caffeine levels did not affect the overall pattern of fatigue or the pattern of recovery from fatigue. Our results suggest that the plasma concentrations found when caffeine is used to enhance athletic performance in human athletes might directly enhance force and power during brief but not prolonged activities. These findings potentially confirm previous in vivo studies, using humans, which implied caffeine ingestion may cause acute improvements in muscle force and power output but would not enhance endurance.     

Oxygen deficits and oxygen delivery kinetics during submaximal intensity exercise in humans after 14 days of head-down tilt-bed rest

The effect of two running sessions completed within a 12-h period on hemolysis, inflammation, and hepcidin activity in endurance athletes was investigated. Ten males completed two experimental trials in a randomized, counterbalanced order. The two trials included (a) a one-running-session trial (T1) including 10 × 1 km interval repeats (90% peak velocity), and (b) a two-running-session trial (T2), comprising a continuous 10-km run (70% peak velocity), and a 10 × 1 km interval run (90% peak velocity) completed 12 h later. Interleukin-6 (IL-6), free hemoglobin (Hb), haptoglobin (Hp), iron, ferritin, and hepcidin were assessed post-exercise. After the T1 and T2 interval runs, free Hb was significantly increased and Hp significantly decreased (p ≤ 0.05), with a cumulative effect shown in T2 after the second run (p ≤ 0.05). The IL-6, serum iron, ferritin, and hepcidin activity were increased after each running session (p ≤ 0.05), with no cumulative effect in T2. In conclusion, a cumulative effect of two running sessions on hemolysis was shown, but no similar effect with inflammation and hepcidin activity was evident.     

Cerebral oxygen saturation and electrical brain activity before,during, and up to 36 hours after arterial switch procedure in neonates without pre-existing brain damage: its relationship to neurodevelopmental outcome

Objective: To monitor the pattern of cerebral oxygen saturation (rSat), by use of NIRS, in term infants before, during and after the arterial switch operation and to evaluate its relation to neurodevelopmental outcome. Methods: In 20 neonates without pre-existing brain damage hemodynamics and arterial oxygen saturation (AO₂-Sat) were monitored simultaneously with rSat and amplitude-integrated EEG (aEEG) from 4 h to 12 h before up to 36 h after cardiopulmonary bypass (CPB) and short duration of cardiac arrest during deep hypothermia (DHCA). The Bayleys developmental scale was performed at 30 months. Results: Before surgery rSat was <50% in 16 patients. During CPB rSat increased to normal values, with a sharp decrease during brief CA (median 6.5 min). Post-CPB rSat showed a transient decrease (30–45%) despite normal PaO₂ with sustained normalization after 6–26 h. Recovery time of the rSat seemed longer when pre-operative rSat was below 35%, and for lower minimum nasopharyngeal temperature and longer duration of CPB and of DHCA. Recovery time of the aEEG varied and did not correlate with normalization of rSat. Neurodevelopmental outcome was normal in all but two patients. Patients with lower pre-operative rSat (<35%) tended to have lower DQ (developmental quotient) scores at 30–36 months. (median: mental 102 and motor 101 (range 58–125) compared with mental 100 and motor 110 (range 83–125)) Conclusion: Despite prompt normalization of circulation and oxygenation after surgery, recovery of rSat of the brain took 6–26 h, probably because of higher energy demand after CPB. Pre-operative cerebral oxygenation may be underestimated as a possible cause of adverse post-operative outcome.     

Assessment of post-competition peak blood lactate in male and female master swimmers aged 40–79 years and its relationship with swimming performance

The main purpose of this study was to measure the post-competition blood lactate concentration ([La]_b) in master swimmers of both sexes aged between 40 and 79 years in order to relate it to age and swimming performance. One hundred and eight swimmers participating in the World Master Championships were assessed for [La]_b and the average rate of lactate accumulation (La′; mmol l⁻¹ s⁻¹) was calculated. In addition, 77 of them were also tested for anthropometric measures. When the subjects were divided into 10-year age groups, males exhibited higher [La]_b than women (factorial ANOVA, P < 0.01) and a steeper decline with ageing than female subjects. Overall, mean values (SD) of [La]_b were 10.8 (2.8), 10.3 (2.0), 10.3 (1.9), 8.9 (3.2) mmol l⁻¹ in women, and 14.2 (2.5), 12.4 (2.5), 11.0 (1.6), 8.2 (2.0) mmol l⁻¹ in men for, respectively, 40–49, 50–59, 60–69, 70–79 years’ age groups. When, however, [La]_b values were normalised for a “speed index”, which takes into account swimming speed as a percentage of world record, these sex-related differences, although still present, were considerably attenuated. Furthermore, the differences in La′ between males and females were larger in the 40–49 age group (0.34 vs 0.20 mmol l⁻¹ s⁻¹ for 50-m distance) than in the 70–79 age group (0.12 vs 0.14 mmol l⁻¹ s⁻¹ for 50-m distance). Different physiological factors, supported by the considered anthropometric measurements, are suggested to explain the results.