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The purpose of this study was to determine the effects of short-term exercise cessation on lipid and lipoprotein profile and insulin sensitivity in highly trained runners (n=12; mean age 19.9 years) and power athletes (n=12; mean age 24.4 years). Following 14 days of exercise cessation, running time to exhaustion and maximal oxygen uptake decreased by 9.2% and 4.8% (P < 0.05) in the runners, while in the power athletes one repetition maximum squat and bench press did not change (P>0.05). No changes occurred in body composition. Data from a 2-h oral glucose tolerance test revealed an impairment of the glycemic state in all athletes (P<0.05). In contrast, exercise cessation did not significantly (P>0.05) alter plasma levels of cholesterol, triglycerides, and low density (LDL) and high density lipoprotein (HDL). No changes were observed in HDL2, HDL2b, and HDL3 subfractions, LDL diameter, and qualitative LDL pattern (P>0.05). These data thus suggest that despite a decrease in insulin sensitivity, short-term exercise cessation, independent of exercise mode, was insufficient to alter plasma lipid and lipoprotein profiles in well-trained athletes.

The purpose of this study was to compare resistance exercise training (RT) to aerobic exercise training (AE) on the clinical risk factors for metabolic syndrome (MetSyn) in physically inactive overweight males (age 27–48 years). Subjects with at least one risk factor for MetSyn performed RT (n = 13, age 35.1 ± 4.7 years, BMI 31.2 ± 2.7 kg/m2) or AE (n = 9, age 37.6 ± 4.9 years, BMI, 31.2 ± 3.2 kg/m2) for 6 months. Training frequency and exercise session duration were equal and by 3 months the subjects exercised 4 day/week for 45 min/session. Blood lipids and glucose, waist circumference, and mean arterial blood pressure (MAP) were measured at 0, 3, and 6 months. A MetSyn z score was calculated for each subject from triglycerides, HDL cholesterol, fasting glucose, waist circumference, and MAP. Statistical significance was set at p ≤ 0.05. No significant differences existed between RT and AE groups at 0 month. AE showed a significant reduction in MetSyn z score from 0 (0.91 ± 3.57) to 6 months (−1.35 ± 2.95), while RT approached significance (p = 0.07) from 0 (0.09 ± 2.62) to 6 months (−1.30 ± 2.22). Triglycerides (mmol/L) significantly decreased in AE from 0 (1.93 ± 0.90) to 6 months (1.41 ± 0.70). Waist circumference (cm) significantly decreased in AE from 0 (106.8 ± 7.3) to 6 months (101.2 ± 6.5), and in RT from 0 (108.4 ± 9.0) to 6 months (105.7 ± 7.0). MAP (mmHg) decreased in RT from 0 (93.8 ± 5.8) to 6 months (87.5 ± 6.1) and in AE from 0 (97.6 ± 7.0) to 6 months (91.3 ± 6.8). With equal training frequency and exercise session duration, both RT and AE training, when paired with energy restriction improve the clinical risk factor profile for MetSyn.

Both exhaustive physical exertion and starvation have been reported to induce depression of immune function. The aim of the present study was to investigate the inflammatory environment and state of activation and mediator-producing potential of circulating leukocytes during prolonged physical activity with concomitant energy and sleep deprivation. Eight well-trained males were studied during 7 days of semi-continuous physical activity. Sleep was restricted to about 1 h/24 h, energy intake to 1.5– 3.0 MJ/24 h. Blood was drawn at 07.00 a.m. on days 0, 2, 4, and 7. Plasma levels of inflammation markers were measured. The response of circulating leukocytes to lipopolysaccharide (LPS; 1 μg mL−1), and the effect of added hydrocortisone (10 and 100 nmol L−1), were measured in the supernatant after 3 h of incubation in an ex vivo whole blood model. Activation of leukocytes steadily increased as measured by plasma matrix metalloproteinase-9, tumour necrosis factor-α, interleukin-1β, and interleukin-6. Inhibitors of systemic inflammation were either unaltered (tissue inhibitor of matrix metalloproteinase-1) or elevated (plasma interleukin-1 receptor antagonist). Cortisol levels increased on days 2 and 4, but thereafter reverted to baseline values. The leukocytes responded to LPS activation with increasing release of inflammatory cytokines throughout the study period. The anti-inflammatory potency of hydrocortisone decreased. Prolonged multifactorial stress thus activated circulating immune cells and primed them for an increased response to a subsequent microbial challenge.

During infusion with adrenaline in healthy subjects there was a more than 50% reduction in serum myoglobin concentrations. This effect appeared to be specific for beta-adrenergic stimulation, since no changes were seen after prior IV beta-blockade with propranolol, nor did noradrenaline affect the serum myoglobin levels. Oral beta-blockade with propranolol raised the basal serum levels of myoglobin and enhanced the exercise-related rise in serum myoglobin concentrations during ergometer cycling to exhaustion. These observations thus indicate that the beta-adrenergic system affects serum myoglobin concentrations. This should be kept in mind in the evaluation of myoglobin measurements for clinical purposes, and might reflect a physiologically relevant mechanism.

We investigated the prevalence of exercise-associated hyponatremia (EAH) in 25 male and 11 female open-water ultra-endurance swimmers participating in the ‘Marathon-Swim’ in Lake Zurich, Switzerland, covering a distance of 26.4 km. Changes in body mass, fat mass, skeletal muscle mass, total body water, urine specific gravity, plasma sodium concentration [Na+] and haematocrit were determined. Two males (8%) and four females (36%) developed EAH where one female was symptomatic with plasma sodium [Na+] of 127 mmol/L. Body mass and plasma [Na+] decreased (p < 0.05). The changes in body mass correlated in both male and female swimmers to post-race plasma [Na+] (r = −0.67, p = 0.0002 and r = −0.80, p = 0.0034, respectively) and changes in plasma [Na+] (r = −0.68, p = 0.0002 and r = −0.79, p = 0.0039, respectively). Fluid intake was neither associated with changes in body mass, post-race plasma [Na+] or the change in plasma [Na+]. Sodium intake showed no association with either the changes in plasma [Na+] or post-race plasma [Na+]. We concluded that the prevalence of EAH was greater in female than in male open-water ultra-endurance swimmers.

Ageing is associated with an increased susceptibility to muscle damage but little is known on how this affects muscle recovery after exercise. Hence, this study is aiming at investigating the effects of a heavy-resistance training session of neuromuscular recovery of the calf muscles of a group of elderly men aged >65. Maximal isometric and isokinetic torque, muscle voluntary activation (VA) capacity, surface electromyographic activity (EMG), peak-to-peak amplitude of action potentials associated with twitch responses of plantar flexors were evaluated before and 5 min (post1), 24 h (post2) and 48 h (post3) after 10 sets of 10 repetitions of a calf raise exercise performed at an intensity of 70% of the individual, one repetition maximum. Blood samples were taken before and 1, 48, 96 and 144 h after the training session and assayed for serum creatine kinase (CK), lactate dehydrogenase (LDH) and myoglobin (Mb). Peak torque during eccentric and concentric (120° s−1) contractions and twitch parameters were significantly reduced at post1, and recovered completely at post2. No significant changes were found in integrated EMG, M-wave amplitudes and VA throughout the entire test period. CK and LDH concentrations reached peak values 48 h after the exercise session and returned to the pre-exercise values 96 h after the training session. Serum Mb level increased by 73.2% 1 h after exercise and recovered at 48 h. The reduction in peak torque following a strength training session in an elderly population could be explained mainly by fatigue of peripheral origin. After 24 h the elders recovered completely their capacities of strength production, despite muscle damage being still evident 48 h after the strength training session.

The frequent use of the computer mouse was reported to be associated with the development of the musculoskeletal disorders in the wrist, forearm, and shoulder regions. This study was to examine the effect of the mouse weights and operation speeds on the wrist motion and muscle activity. 25 subjects (20 males and 5 females) were instructed to repetitively point-and-click the mouse between two targets displaced in the monitor with five different weighted mice (weights around 70, 100, 130, 160, and 190 g) at the fast (50 repetition/min) and slow (25 repetition/min) operation speeds. Surface electromyographic activity of the extensor carpi radialis, extensor carpi ulnaris, extensor digitorum, and upper trapezius muscles were recorded, and the electrogoniometer was used to register the wrist motions. The results showed that the maximal ulnar deviation was not significantly different among the examined conditions. The wrist movement range and the forearm muscle activities showed a V-shape tendency with the lowest value in the mouse weight of 130 g. This tendency was diminished during the slow speed tasks. The results suggested that the proper mouse weight could benefit the users in terms of increasing the movement efficiency and decreasing the muscular costs.

Serum concentrations of luteinizing hormone (LH), follicle stimulating hormone, testosterone (T) and melatonin were measured in seven physically active male volunteers after exercise on a treadmill using the Bruce protocol. Measurements were made on blood samples obtained before exercise, within 30 s after exercise, at 15 min after exercise, and subsequently at 30-min intervals after exercise for a total duration of 180 min. Serum LH concentration fell from a peak post-exercise level of 15.7 (4.7) IU·l−1 [mean (SD)] to a nadir of 10.3 (2.4) IU·l−1 (P<0.004). Nadir values in individual volunteers were seen between 60 and 150 min after exercise. This fall in serum LH was paralleled by a similar fall in the concentration of serum T. Serum melaonin concentrations did not change significantly after exercise. It is concluded that melatonin, despite is reported anti-gonadotropic properties, does not play a role in the depression of serum LH after acute strenuous exercise in physically active males

Resting metabolic rate (RMR), dietary thermogenesis (DIT), aerobic capacity ( $$\dot V$$ O2 max), and percent body fat were measured in a group of sixteen women and ten men. DIT was significantly positively correlated with aerobic capacity (r=0.658). Percent body fat was significantly negatively correlated with $$\dot V$$ O2 max (r=−0.727). RMR was independent of $$\dot V$$ O2 max, or body fatness, but women had a significantly higher average RMR than men. Three men and three women participated in an endurance training program which significantly increased $$\dot V$$ O2 max. DIT was increased in proportion to the increase in aerobic capacity (r s=0.924), RMR was unchanged, and body fat decreased in males but not females. The controversy surrounding “luxuskonsumption” may stem in part from not taking into account individual differences in aerobic capacity when measuring DIT.

Two studies were undertaken to determine whether firefighter instructors are capable of performing a simulated rescue task after undertaking a live fire training exercise (LFTE) lasting approximately 40 min. In the first study, ten instructors performed two simulated rescue tasks in air at 19°C, involving dragging an 81-kg dummy for 15 m along a corridor and down two flights of stairs. The first rescue acted as a control (Rcontrol) and was conducted when they were euhydrated and normothermic. The second task was undertaken 10.4 (3.3) min [mean (SD)] after a LFTE resulting in an average rectal temperature of 38.1 (0.4)°C (Rhot). All instructors were able to successfully complete Rcontrol and Rhot in 90.1 (28.6) s and 78.7 (15.6) s respectively. Heart rate (HR) and rating of perceived exertion (RPE) were higher after the LFTE [162 (16) beats min−1 versus 180 (15) beats min−1; and 13.3 (2.4) versus 15.7 (2.1), respectively, P<0.001]. In the second study, six instructors (one instructor participated twice giving seven trials) undertook a simulated rescue task in 16°C involving dragging an 85-kg dummy along a flat surface 79 (65) s after a LFTE that increased rectal temperature to 38.3 (0.7)°C. On six occasions the instructor was able to successfully complete the full 30-m drag in 41.7 (6.9) s and one instructor dragged the dummy for 20 m before stopping through exhaustion. HR during the rescue task reached 173 (19) beats min−1 and RPE was 16.3 (2.4). In conclusion, most of the instructors were able to perform a rescue task after the LFTE, however they were close to their physical limit.