The energy cost of level walking before and after hydro-kinesi therapy in patients with spastic paresis

In this study the energy cost of level walking was measured in 23 patients with stationary spastic paresis before and after a two-week treatment (45 min daily) of hydro-kinesi therapy, the latter consisting of passive and active movements in warm (32°C) sea water, free swimming and water immersion walking. Among the subjects (80.2±13.2 kg body mass; 56.0±14.6 years of age; 10.7±6.6 years of duration of spasticity), 12 were affected by hemiparesis, 4 by multiple sclerosis and 7 by spinal cord injury. The energy cost of level walking (C_w) was measured before and after therapy from the ratio of the overall steady-state oxygen consumption to the effective speed of progression. The differences in C_w due to the treatment, at matched speeds, were found to be negligible at speeds higher than 0.75 m · s⁻¹ (less than 5%) but to increase, with decreasing speed, up to about 17% at 0.1 m · s⁻¹. The treatment was therefore effective in improving the gait characteristics of the subjects, through a decrease of their C_w, mainly at low speeds of progression.     

Field measurements of oxygen uptake in elite orienteers during cross-country running using telemetry

Oxygen uptake (V_o2) was measured and economy calculated during running on a treadmill and during cross-country running in 14 male and 9 female orienteers using a telemetric system (K-2, Cosmed, Italy). The cross-country route comprised 3 parts: horizontal path running, horizontal running in light terrain and running in heavy terrain with obstacles and steep hills. Each subject accomplished the whole test route at a speed corresponding to 96±5% of maximal speed and at maximal speed. The running time at maximal speed was 19±3 min. The running economy was similar in treadmill and path running (211 ± 10 vs 210± 14 ml · kg⁻¹· km⁻¹), but V_o2 per km increased in light and heavy terrain to 290 ± 16 and 362±18 ml · kg⁻¹· km⁻¹, respectively. There was no difference in running economy between men and women. The elite group (5 men and 3 women) demonstrated 5% better running economy than the sub-elite (9 men and 6 women) during running in light and heavy terrain, whereas no difference was seen during treadmill and path running. In conclusion, elite orienteers have better running economy in light and heavy terrain than sub-elite orienteers.     

Salbutamol and high-intensity treadmill running in nonasthmatic highly conditioned athletes

Salbutamol is a widely used drug among elite athletes. We wanted to provide more information on the effects of salbutamol in nonasthmatic athletes. Seventeen highly conditioned male athletes (Vo_2max > 70 ml · kg⁻¹· min⁻¹) participated in a randomized, double-blind and placebo-controlled cross-over study. Nebulized salbutamol (0.05 mg/kg) or placebo was inhaled prior to a high intensity (110% of Vo_2max) treadmill run to exhaustion. The measured variables included endurance time, oxygen uptake, ventilation, breathing rate, heart rate, and oxygen saturation. Lung function was measured as forced expiratory volume in the first second (FEV₁) before and after medication, and during the recovery from the run. The high intensity runs led to total exhaustion after 4–10 min. A close-to-significant shortening in endurance time was found when salbutamol was given. During the running (0–4 min) the oxygen uptake was slightly lower and the heart rate was slightly higher when salbutamol was given. No differences were found in peak oxygen uptake, peak heart rate, ventilation, breathing rate or oxygen saturation. FEV₁ reflected an increase in airway caliber after the inhalation of salbutamol. These changes were still present in the recovery from the test run with the exception of the measurement immediately after the exercise. Although evidence for β-adrenergic stimulation was found, it was concluded that a therapeutic dose of nebulized salbutamol does not improve performance in highly trained athletes during a high-intensity run to exhaustion.     

Blood sampling during continuous running and 30-second intervals on a treadmill

The aim of the study was to investigate whether results from lactate threshold tests on a treadmill would be influenced by collecting blood during 30-s intervals (INT) as compared to sampling during continuous running (CONT). Ten well-trained middle- and long-distance runners ran the two protocols randomly on separate days, with the same speed both times. Values of blood lactate, heart rate and ratings of perceived exertion (RPE) were compared. The results showed no significant difference in any of the variables comparing the two regimens. During CONT and INT, running speed at 4.0 mmol · l⁻¹ was 18.6 (±1.2) and 18.7 (±1.2) km · h⁻¹, HR 182 (±10.7) and 183 (±8.1) beats · min⁻¹, respectively. Also at the 2 and 3 mmol · l⁻¹ level there were no significant differences in running speed or heart rate. RPE values of legs and breathing at the final speed, just above the 4 mM level, showed no significant difference. It is concluded that, for well-trained middle- and long-distance runners, any of the two regimens can be chosen without affecting the lactate threshold results.     

Lactate/H+ transport in skeletal muscle from spinal-cord-injured patients

In order to evaluate the effect of prolonged muscle inactivity on sarcolemmal lactate/H⁺ transport in humans, the lactate/H⁺ transport capacity was determined in the thigh muscle of spinal-cord-injured (SCI) individuals. The lactate transport rate was measured in sarcolemmal giant vesicles produced by collagenase treatment of muscle biopsies obtained from the vastus lateralis muscle. Six SCI subjects with total loss of motor and sensory functions of their lower limbs participated in the study. The duration of the injury ranged from 2 to 15 years. The total lactate transport rate in the muscle of SCI patients was 46.5±2.6 pmol · cm⁻²· s⁻¹ (mean±SEM), which corresponds to a 17% lower (P<0.05) transport rate than that found in healthy, untrained subjects. The estimated carriermediated lactate/H⁺ transport capacity was approximately 26% lower in the SCI patients than in healthy, untrained subjects. The observed muscle lactate/H⁺ transport capacity of SCI individuals is in accordance with a positive correlation between the capacity of the lactate/H⁺ transporters and the percentage occurrence of slow-twitch fibres in a muscle, although there seems to be a wide range of transport capacities within each fibre type. The present results show that the sarcolemmal lactate/H⁺ transport capacity is lower in SCI individuals than in normally physically active subjects, which indicates that prolonged muscle inactivity reduces the lactate/H⁺ transport capacity of human muscle.     

Factors influencing assessment of maximal heart rate

The significance of warm-up time, time and number of runs, treadmill inclination and the degree of being rested for the assessment of maximal heart rate (HR_max were studied in 59 athletes. A protocol of 2 subsequent 3- to 4-min runs to exhaustion gave the highest average peak HR values. Being rested before the start of the test and the warm-up time were both decisive in reaching HR_max. Peak HR from field tests were significantly lower than values attained from lab tests. Mean peak HR from maximal oxygen uptake measurements were 5–6 beats · min⁻¹ lower than values from the specially designed HR_max test described above.     

Aerobic and anaerobic exercise capacities of elite middle-distance runners after two weeks of training at moderate altitude

The effect of short-term altitude training on sea-level physiological characteristics in elite runners was investigated. Seven middle-distance runners (6 men, 1 woman) belonging to the Swedish national team (mean age 23 years) spent 2 weeks of training at 2000 m above sea level in Kenya. Treadmill tests were performed before and 6 and 12 d after the altitude sojourn. Six other runners (4 men, 2 women) had a corresponding training sojourn at sea level in Portugal (control group). Ro of the runners (1 man, 1 woman) in the Kenya group were omitted from the study because of gastroenteritis. The maximal oxygen uptake (VO_{2 max}; pretravel: Kenya group 212 and control group 188 ml · kg^−0.75 - min⁻¹), maximal treadmill time and oxygen cost of running were unchanged in both groups. The maximal oxygen deficit increased in all subjects after the Kenya sojourn (mean 19±6%). Heart rates during running at specified submaximal running velocities were lower post-altitude (Kenya group), but tended to be higher after sea-level training (control group). Maximal heart rate was unchanged in both groups. Perceived exertion (Borg) during submaximal running was lower post-altitude. Submaximal and maximal blood lactate and plasma catecholamine concentrations were not altered in any of the groups. Post-exhaustive plasma ammonia levels were decreased 12 d after altitude descent in the Kenya group. The results suggest an unchanged aerobic capacity in elite middle-distance runners after short-term training at moderate altitude. However, a change in the circulatory regulation during submaximal exercise was observed. Furthermore, anaerobic capacity improved but this bore no clear relation to lactate or ammonia metabolism.     

Maximal and submaximal oxygen uptake during running: how should body mass be accounted for?

Oxygen uptake during running, i.e., the running economy, is an important factor in determining running performance in endurance events. The relation to performance is particularly strong when the aerobic running capacity is calculated, i.e., when running economy is related to the maximal oxygen uptake. There is considerable interindividual variation in running economy, and the reason for this is only partly understood. To some extent, this may be due to the way in which the oxygen uptake during running is usually expressed. This may expecially be true when subjects with different or changing body masses are compared. Several lines of evidence, including earlier animal studies as well as more recent human studies, favor the expression of submaximal and maximal oxygen uptake during running in terms of ml · kg^−0.75· min⁻¹ rather than as ml · kg⁻¹· min^−1.     

The magnitude of muscle strain does not influence serial sarcomere number adaptations following eccentric exercise

The hypothesis of the present study was that low-repetition and high-impact training of 10 maximum vertical jumps/day, 3 times/week would be effective for improving bone mineral density (BMD) in ordinary young women. Thirty-six female college students, with mean age, height, and weight of 20.7±0.7 years, 158.9±4.6 cm, and 50.4±5.5 kg, respectively, were randomly divided into two groups: jump training and a control group. After 6 months of maximum vertical jumping exercise intervention, BMD in the femoral neck region significantly increased in the jump group from the baseline (0.984±0.081 vs 1.010±0.080 mg/cm²; P <0.01), although there was no significant change in the control group (0.985±0.0143 vs 0.974±0.134 mg/cm²). And also lumbar spine (L(2–4)) BMD significantly increased in the jump training group from the baseline (0.991±0.115 vs 1.015±0.113 mg/cm²; P <0.01), whereas no significant change was observed in the control group (1.007±0.113 vs 1.013±0.110 mg/cm²). No significant interactions were observed at other measurement sites, Ward's triangle, greater trochanter, and total hip BMD. Calcium intakes and accelometry-determined physical daily activity showed no significant difference between the two groups. From the results of the present study, low-repetition and high-impact jumps enhanced BMD at the specific bone sites in young women who had almost reached the age of peak bone mass.     

Concurrent validity of the PAM accelerometer relative to the MTI Actigraph using oxygen consumption as a reference

The purpose of this study was to examine the concurrent validity of the Personal Activity Monitor (PAM) accelerometer relative to the Actigraph accelerometer using oxygen consumption as a reference, and to assess the test–retest reliability of the PAM. Thirty-two fit, normal weight adults (aged 21–54) performed two activities, treadmill walking and stair walking, while wearing the PAM, the Actigraph and the Cosmed K4b². Correlation coefficients and agreement in absolute energy expenditure (EE) levels between PAM, Actigraph and Cosmed were calculated. The test–retest reliability was examined among 296 PAM's using a laboratory shaker. Intraclass correlation coefficients (ICC) and coefficient of variation (CV) were determined. Correlations for treadmill walking and stair walking, respectively, were r ²=0.95 and r ²=0.65 for PAM with Actigraph, r ²=0.82 and r ²=0.93 for PAM with VO₂ and r ²=0.64 and 0.74 for Actigraph with VO₂. Both the PAM and Actigraph underestimated EE during treadmill and stair walking by a substantial amount. The test–retest reliability of the PAM was high [ICC=0.80; 95% confidence interval (CI) (0.28;0.92) and intra-CV=1.5%]. The PAM and Actigraph accelerometer are comparable in assessing bodily movement during treadmill and stair walking. The PAM is a valid device to rank subjects in EE and can be useful in collecting objective data to monitor habitual physical activity.     

Salmeterol and physical performance at -15°C in hghly trained nonasthmatic cross-country skiers

The aim of this double-blind. placebo-controlled, cross-over study was to investigate possible improvement in physical performance at an ambient temperature of −15°C by an inhaled dose of 50 μg salmeterol in 8 highly trained nonasthmatic cross-country skiers. FEV₁ was measured before, during and after the treadmill exercise protocol, which consisted of a warm-up run. runs of 10 min at 90%, and 5 min at 80% V O_2max, followed by a timed run to exhaustion. Despite a significant improvement in FEV₁, salmeterol did not have a beneficial effect on heart rate, blood lactate concentration, respiratory exchange ratio, oxygen uptake or minute ventilation during the exercise protocol. Running time to exhaustion was not significantly different from placebo. This lack of enhancement of exercise performance in healthy endurance athletes further supports the recent approval of salmeterol for prophylactic use by asthmatic athletes during training and competition.     

Follow-up studies of group behavior therapy for obese Japanese patients

Follow-up results of 141 patients with simple obesity were compared with those of 147 obese subjects who did not take part in the group behavior therapy comprising comprehensive guidance for daily diet and physical exercise. The initial body weight of the therapy and the control groups was 83.6 ± 1.2 kg (body mass index: 29.7 ± 0.3 kg/m²) and 80.4 ± 0.8 kg (29.0 ± 0.2 kg/m²), respectively. After 6 months, a 4.7 ± 0.5 kg weight loss of the therapy group was significantly greater than only a 1.2 ± 0.4 kg weight loss of the control group. Paper questionnaires concerning the longterm results showed that pup behavior therapy is effective for at least 3–4 years in the case of obese Japanese patients. Therefore, group therapy sessions should be recommended at 3- to 4-year intervals.     

Effect of erythropoietin administration on mammal aerobic power

The effects of subcutaneous injections of human erythropoietin (rhEpo) on the circulatory response to submaximal and maximal exercise were studied in healthy male subjects ( n =15). Hemoglobin concentration [Hb] increased from 152 g · l⁻¹ to 169 g · l⁻¹ and in parallel maximal aerobic power (Vo_2max) increased from 4.52 to 4.88 l · min⁻¹. There were no significant changes in heart rate, ventilation and blood lactate concentration during the exhausting run. Compared with infusion of red blood cells, there was no significant difference in the increase in Vo_2max per gram increase in [Hb]. Systolic blood pressure at 200 W increased from before rhEpo treatment to afterwards. It was concluded that slow (rhEpo treatment) and acute (red blood cell reinfusion) increase of [Hb] resulted in similar increase in Vo_2max.     

The relationship of sustained exercise training and bone mineral density in aging male runners

Fifty-six men aged 42–73 years (50.2±10.0 years), who were competitive distance runners 20–25 years previously, were examined for bone mineral density (BMD) to determine the relationship between sustained distance running and BMD. Subjects were classified as being highly trained (HT, n =17), moderately trained (MT, n =29) or untrained (UT, n =10) according to their training in recent years. Subjects in each group were of similar age (HT 46.5±2.01, MT 53.0±1.51, UT 46.7±2.44 years) and lean body mass. Total body weight (kg) and percentage fat, however, were significantly greater ( P <0.05) in the UT group than in either the MT or HT groups (UT 80.6±2.44 kg, 22.0±1.16%; MT 74.9±1.51 kg, 17.5±0.61%; HT 70.5±1.71 kg, 13.5±0.59%). Lumbar vertebrae and hip region BMD (g·cm⁻²) was determined via dual energy X-ray absorptiometry (DEXA). No differences in BMD were found among the three groups in either the lumbar (HT 1.00±0.02, MT 1.02±0.03, UT 1.07±0.04 g·cm⁻²) or the hip regions (HT 0.99±0.03, MT 0.98±0.02, UT 1.06±0.04 g·cm⁻²). Furthermore, none of the groups had BMD that was significantly different from age-matched normative values taken from a reference database. A moderate correlation was found between body weight and BMD when combining all subjects ( r =0.38 for lumbar and r =0.41 for hip). These results indicate that middle-aged to older males who have sustained exercise training in the form of running do not have significantly different lumbar vertebrae or hip region BMD compared to individuals who run less or not at all.     

Development of muscular endurance and strength from adolescence to adulthood and level of physical capacity in men and women at the age of 34 years

This study investigated the development of muscular endurance and strength from the age of 16 to the age of 34 and the fitness components at the age of 34 in men and women. A randomly selected group consisting of 220 boys and 205 girls was tested in 1974 and reinvestigated 18 years later. Muscular endurance and strength increased significantly in 4 of the 5 remeasured tests for the men; bench press increased by 58%, two-hand lift by 20%, hand grip by 16% and Sargent jump by 8%. For the women there was a significant increase in bench press and two-hand lift by 25% and 7% respecively, but hand grip and Sargent jump decreased with a few per cent. The hip and trunk flexion test, sit-up, decreased remarkably in both men (58%) and women (78%). At the age of 16 physical capacity was significantly higher in all tests in the men. This was also the situation at the age of 34 except for VO₂ max in ml. kg⁻¹. min⁻¹ and muscular endurance in the back muscles. There were no differences in flexibility between men and women except for less flexibility in the hamstring muscles in the men. The result of the balance test was significantly better in the men.     

Cardiovascular changes with age and exercise

Various studies report a 0–22% per decade decline in circulatory function (VO_2max) with advancing age. Twelve exercising men (E) were followed for 28 years, mean age 43 and 71 years, initial to final measurement, while 12 dropouts (C) detrained for 21 years, with a mean age from first to last measurement of 48 and 69 years, respectively. VO₂ max in E changed from 45.9 to 39.4 ml · min⁻¹· kg⁻¹, 5% per decade, whereas C declined from 36.0 to 21.4 ml min⁻¹· kg⁻¹, 19% per decade. Resting blood pressure was unchanged in E, 119/75 mmHg, whereas C rose from 128/85 to 149/90 mmHg. The data suggest that regular aerobic exercise forestalls the usual loss of circulatory function with increasing age.     

The effect of aerobic training in girls with idiopathic scoliosis

The purpose of the present study was to investigate the effect of aerobic training in girls with idiopathic scoliosis, in selective respiratory parameters (VC, FVC, FEV₁, FEV₁/VC% FEV₁/FVC) as well as the ability to perform aerobic work (PWC₁₇₀). The training group consisted of 20 young girls with a mean age of 13.51±0.16 years. They wore a Boston-type brace for a mean period of 0.30±0.04 years and suffered from a scoliotic curve (27.4±1.9°). They followed a two-month training program on the cycloergometer. Each training session lasted 30 min and was performed four times a week. The control group consisted of 20 girls with a mean age of 13.61±0.18 years and they wore the same type of brace for a mean period of 0.24±0.04 years. They also suffered from a scoliosis (29.5±1.8°). The results of the study revealed that aerobic training sustained (VC, FEV₁, FEV₁/VC) or improved significantly (FVC, FEV₁/FVC) the parameters of pulmonary function, while the respective parameters (VC, FVC) for the control group were reduced during the two-month period. The ability to perform aerobic work increased 48.1% ( P <0.01) in the training group, while it decreased 9.2% ( P <0.01) in the control group.     

Prevalence of asthma-like symptoms, asthma and its treatment in elite athletes

The objective was to determine the prevalence of asthma-like symptoms and asthma and the use of asthma medication in Danish elite athletes. A cross-sectional questionnaire survey of Danish elite athletes was conducted in 2006. All elite athletes ( N =418) financially supported by the national organization of elite athletes comprised the study group; 329 (79%) completed the questionnaire concerning their sport, asthma-like symptoms, asthma and use of asthma medication. Asthma-like symptoms at rest were reported by 41% of respondents; 55% reported asthma-like symptoms at rest or at exercise. Physician-diagnosed asthma was present in 16% and 14% had current asthma. Asthma medication was taken by 7% of the athletes, of whom 79% used inhaled corticosteroids and 21% used inhaled β₂-agonists only. Athletes participating in endurance sports had higher prevalences of current asthma (24%) and use of asthma medication (15%) than all other athletes ( P <0.01). Athletes participating in endurance sports have a higher prevalence of asthma and use of asthma medication. The frequency of asthma medication is lower than the prevalence of current asthma indicating that there is no overuse of asthma medication among Danish elite athletes.