Moderate-intensity interval training increases serum brain-derived neurotrophic factor level and decreases inflammation in Parkinson's disease patients.

It has been demonstrated that physical training increases serum brain-derived neurotrophic factor (BDNF) in healthy people. The aim of this study was to establish the effect of physical training on the basal serum level of the BDNF in the Parkinson's disease patients (PD patients) in relation to their health status. Twelve PD patients (mean ± S.E.M: age 70 ± 3 years; body mass 70 ± 2 kg; height 163 ± 3 cm) performed a moderate-intensity interval training (three 1-hour training sessions weekly), lasting 8 weeks. Basal serum BDNF in the PD patients before training amounted to 10,977 ± 756 pg x mL(-1) and after 8 weeks of training it has increased to 14,206 ± 1256 pg x mL(-1) (i.e. by 34%, P=0.03). This was accompanied by an attenuation of total Unified Parkinson's Disease Rating Scale (UPDRS) (P=0.01). The training resulted also in a decrease of basal serum soluble vascular cell adhesion molecule 1 (sVCAM-1) (P=0.001) and serum tumor necrosis factor-α (TNF-α) (P=0.03) levels. We have concluded that the improvement of health status of the Parkinson's disease patients after training could be related to the increase of serum BDNF level caused by the attenuated inflammation in those patients.

Mechanomyography and electromyography during and after fatiguing shoulder eccentric contractions in males and females.

The aim of this study was to investigate changes in mechanomyographic (MMG) and the surface electromyographic (EMG) signals during and after fatiguing shoulder eccentric contractions in a group consisting of 12 males and 12 females. Exerted force, MMG, EMG, pain and rate of perceived exertion were assessed before, during and after repeated high-intensity eccentric exercises. Bouts of eccentric contractions caused a decrease in the exerted force for males (P<0.05) and an increase in the rate of perceived exertion and pain for both genders (P<0.05). During eccentric exercise, the root mean square (RMS) values of the MMG signal increased (P<0.05). The mean power frequency (MPF) values of the EMG signal decreased at the end of each eccentric bout for both genders (P<0.05); the decrease was higher for females compared with males (P<0.05). Immediately after eccentric exercise in static abduction of the upper limbs, the MMG RMS and MPF values increased (P<0.05). The present study showed that (1) neuromuscular changes associated with pain and changes in muscle stiffness and (2) changes in motor units strategy during fatigue development in shoulder muscle are reflected in the MMG and EMG signals.

Age, sex, race, initial fitness, and response to training: the HERITAGE Family Study.

Effects of age, sex, race, and initial fitness on training responses of maximal O(2) uptake (VO(2 max)) are unclear. Data were available on 435 whites and 198 blacks (287 men and 346 women), aged 17-65 yr, before and after standardized cycle ergometer training. Individual responses varied widely, but VO(2 max) increased significantly for all groups. Responses by men and women and by blacks and whites of all ages varied widely. There was no sex difference for change (Delta) in VO(2 max) (ml. kg(-1). min(-1)); women had lower initial values and greater relative (%) increases. Blacks began with lower values but had similar responses. Older subjects had a lower Delta but a similar percent change. Baseline VO(2 max) correlated nonsignificantly with DeltaVO(2 max) but significantly with percent change. There were high, medium, and low responders in all age groups, both sexes, both races, and all levels of initial fitness. Age, sex, race, and initial fitness have little influence on VO(2 max) response to standardized training in a large heterogeneous sample of sedentary black and white men and women.

The influence of elbow joint angle on different phases of force development during maximal voluntary contraction.

The first aim of the study was to find an elbow joint angle at which muscle can produce maximum voluntary force (Lo(MVC)) and to compare that angle with an angle at which the fastest rates of force development occur (Lo). The second aim of the study was to find if changes in MVC and force development speed at an angle smaller (Ls) and larger (Ll) than the optimal angle depend on whether Ls and Ll were compared to Lo or Ls and Ll to Lo(MVC). Twenty-four male physical education students were tested four times using the BIODYNA dynamometer to measure torque versus time at an optimal length, as well as at lengths that were shorter (Ls = optimal -30 degrees) and longer (Ll = optimal +50 degrees). The average values of optimal angles for force development indices (Lo) were similar to the angle at which maximum force was produced (Lo(MVC)); however, there was a small (5-10 degrees) difference between Lo and Lo(MVC) in the majority of subjects. The results showed that during elbow flexion with the forearm in the midrange position, the difference between Lo and Lo(MVC) was small and did not affect MVC; however, it had a significant effect on the relation between joint angle and force development speed.

Adaptation to a standardized training program and changes in fitness in a large, heterogeneous population: the HERITAGE Family Study.

PURPOSE: This paper describes the variations in response to a standardized, computer-controlled training program. METHODS: Steady-state heart rate (HR) and oxygen intake (VO2) of 614 healthy, sedentary men and women aged 16-65 yr were measured during three cycle ergometer exercise tests. The HR associated with 55, 65, 70, and 75% of each subject's pretraining VO2max was used to prescribe exercise intensity. Subjects exercised three times a week, beginning at a HR associated with 55% VO2max for 30 min. Duration and intensity was gradually increased over 20 wk of training. The duration and HR of each training session were controlled by a computer. RESULTS: Using the linear relationship between HR, VO2 and power output (PO), PO were predicted for each of 60 training sessions at the respective programmed HR. The average ratio of the actual training HR to programmed HR was 0.99. It was hypothesized that participants whose actual training PO exceeded their predicted PO would improve VO2max more than those whose actual PO was less than their predicted PO. Using the ratio of actual/predicted PO determined after the training was over, participants were arbitrarily assigned to three groups: 128 participants had low (LO) ratios (0.65-0.84), 408 had average (AV) ratios (0.85-1.14), and 78 had high (HI) ratios (1.15-1.34). Secondary analysis showed that the training program significantly increased mean VO2max of all three groups. Those who had a smaller increase in training PO (LO) had significantly less increase in VO2max than those with larger increases in PO (HI). CONCLUSION: People who exercise at a HR associated with the same %VO2max can vary substantially in their training PO, in their rate of increase in PO over a 20-wk training program, and in improvement of their VO2max.

Reproducibility of maximal exercise test data in the HERITAGE family study.

PURPOSE: The reproducibility of responses to maximal cycle ergometer testing was determined using data from the HERITAGE Family study at four Clinical Centers in the United States and Canada. METHODS: Reproducibility was determined from maximal exercise test data obtained a) on 2 d in a sample of 390 subjects (198 men and 192 women), b) across 4 d in an Intracenter Quality Control (ICQC) substudy with 55 subjects who were not part of the main study, and c) across 2 wk in a Traveling Crew Quality Control (TCQC) substudy with the same eight subjects who were tested at each of the four centers. Reproducibility was evaluated using technical errors, coefficients of variation (CV) for repeated measures, and intraclass correlation coefficients (ICC) for selected variables obtained on the main cohort, as well as on the ICQC and TCQC substudies. RESULTS: With the exception of systolic and diastolic blood pressures and respiratory exchange ratio, all the other variables (heart rate, ventilation, VO2, and VCO2) were highly reproducible, with CV below 10% and ICC over 0.86. These results were similar to those previously reported on the same subjects at a submaximal power output associated with 60% VO2max. Results were consistent for the main cohort, the ICQC sample, the TCQC sample, and across all four Clinical Centers. CONCLUSIONS: Day-to-day variations are small and reproducibility is high for maximal values of heart rate, ventilation, VO2 and VCO2 at each of the four Clinical Centers of the HERITAGE Family Study.

Comparison of treadmill and cycle ergometer measurements of force-velocity relationships and power output.

Since body balance and weight-bearing factors present while running on the treadmill might cause additional muscle recruitment and thus could influence the force-velocity relationship and power, the present study was undertaken to find out whether the F-V and F-P relationships measured while running on the treadmill are different from the respective indices measured during cycling. On two separate occasions, 32 male subjects were tested using a series of 5 sec, all-out sprints against different braking forces on the Gymrol Sprint treadmill and on the Monark ergometer. The maximal peak power (PPmax) and maximal mean power (MPmax) were measured. The equation: EP = 0.5 maximal force (Fo) x0.5 maximal velocity (Vo) was used to calculate the estimated values of peak power (EPP) and mean power (EMP). The F-V relationship was linear in both cycle ergometer and treadmill measurements. PPmax, MPmax, EPP, and EMP values on the treadmill were lower than the respective values on the ergometer. EPP on the ergometer and on the treadmill, as well as EMP values on the ergometer, were slightly higher than the corresponding measured values of PPmax and MPmax. The levels of braking force at which PP, MP, PPmax, and MPmax were obtained were lower on the ergometer than on the treadmill. High correlation coefficients were found between PPmax, MPmax, EPP, and EMP measured on the ergometer and on the treadmill (r = 0.86, r = 0.84, r = 0.71, r = 0.78, respectively, P<0.01). In both tests, significant relationships between PPmax, MPmax, EPP, and EMP were observed. It is concluded that independent of the type of ergometry the force-velocity relationship is similar in the measured range of velocities which suggests that the number of muscle groups and joints engaged in movement are more important than body balance and weight-bearing factors present while running on a treadmill.

The influence of intermittent fatigue exercise on early and late phases of relaxation from maximal voluntary contraction.

Twenty-two young male subjects were tested to estimate the behavior of the early and late phases of relaxation from a 3-s maximal voluntary contraction (MVC) under the influence of fatigue. Less demanding and more demanding protocols of intermittent hand grip exercise were used to fatigue muscle. Before and after fatigue, the early and late relaxation time, maximal relaxation rate, and half-relaxation time were measured. The results showed that during voluntary movement (a) the early phase of relaxation was independent of the mode of intermittent exercise and did not change significantly after fatigue; (b) the late relaxation time and absolute maximal relaxation rate were slower after both protocols, with the changes more pronounced following the more demanding protocol; and (c) the half-relaxation time and relative maximal relaxation rate were changed only in the more demanding protocol. It is concluded that unlike the relaxation following electrical stimulation of isolated muscle, the early phase of relaxation from voluntary contraction appears to be the most resistant to the type of intermittent fatiguing exercise used in the present study, whereas the late relaxation time was the most sensitive to this type of fatigue.