Masaki Takeda

Assessment of exercise-induced alterations in body composition of patients with coronary heart disease*

SummaryThe porpose of this study was to determine the effects of exercise habituation on body composition and anthropometric characteristics in cardiac patients. The subjects, comprising 20 patients with coronary heart disease, aged 43–69, participated in our supervised exercise programme for 38.0 (SD 12.5) weeks while in hospital. The intensity of most exercise was set at the lactate threshold. Analyses of the data indicated that small but significant reductions were observed in body mass (mb) [−1.4 (SD 1.8) kg], abdominal girth [−1.4 (SD 2.6) cm], chest girth [−1.3 (SD 1.8) cm], body mass index [−0.6 (SD 0.7)], and skinfold thicknesses at all the sites measured. As expected, fat-free mass, derived from either bio-electrical impedance (BI) or a skinfold technique with commonly used regression equations, remained essentially unchanged, while there were significant decreases in body fat (BF) and %BF. The absolute amount of change in mb (i.e. Δmb) was significantly associated with Δabdominal girth (r=0.506), ΔBF estimated by the BI technique (r=0.476), and ΔBF estimated by the skinfold technique (r=0.451). Although the period of the exercise programme [38.0 (SD 12.5) weeks] varied greatly among subjects, it was found not to be associated with Δmb and alterations in body composition. We concluded that aerobic exercise induced significant decreases in BF and many anthropometric variables, independent of the duration of exercise, and that a combination of abdominal girth, BI and/or skinfold measurements would be advantageous in estimating primarily exercise-induced alterations in BF in cardiac patients.

High altitude exposure alters gene expression levels of DNA repair enzymes, and modulates fatty acid metabolism by SIRT4 induction in human skeletal muscle.

We hypothesized that high altitude exposure and physical activity associated with the attack to Mt Everest could alter mRNA levels of DNA repair and metabolic enzymes and cause oxidative stress-related challenges in human skeletal muscle. Therefore, we have tested eight male mountaineers (25-40 years old) before and after five weeks of exposure to high altitude, which included attacks to peaks above 8000m. Data gained from biopsy samples from vastus lateralis revealed increased mRNA levels of both cytosolic and mitochondrial superoxide dismutase. On the other hand 8-oxoguanine DNA glycosylase (OGG1) mRNA levels tended to decrease while Ku70 mRNA levels and SIRT6 decreased with altitude exposure. The levels of SIRT1 and SIRT3 mRNA did not change significantly. However, SIRT4 mRNA level increased significantly, which could indicate decreases in fatty acid metabolism, since SIRT4 is one of the important regulators of this process. Within the limitations of this human study, data suggest that combined effects of high altitude exposure and physical activity climbing to Mt. Everest, could jeopardize the integrity of the particular chromosome.

Physical Motion Analysis of Nordic Walking (P77)

Recent years have seen a worldwide increase in people participating in Nordic Walking with a heavy concentration in Northern Europe. This trend has led to abundant research in Nordic Walking and to reports that this type of exercise is effective in reducing load on the lower limbs. At the same time, there has been no comprehensive experimental study to our knowledge on what change in muscular activity brings about this load-reduction effect. To clarify the exercise structure of Nordic Walking and particularly the mechanism behind this load-reduction effect on lower limb joints, this study simultaneously measured the load on lower limb joints during Nordic Walking on a level surface and the amount of muscular activity at 16 locations on the upper and lower limbs and compared the results with ordinary walking. Results revealed a decrease of 8% or greater in the downward force perpendicular to the floor at each lower limb joint suggesting a reduction in load on lower limb joints. They also showed that differences in lower-limb muscular activity were great at the knee extensor muscles of gastrocnemius and quadriceps femoris. In the upper limbs, all measured locations exhibited an increase in muscular activity with difference in activity of flexor carpi radialis being particular large compared to that of other muscles. These results indicate that bodily movement in Nordic Walking has the potential of reducing load on lower limb joints.

Evaluation of Blood Lactate and Plasma Insulin During High-intensity Exercise by Antecubital Vein Catheterization

The measurement of metabolic and endocrinal markers during physical activity is of relevance to understanding the physiological implications of different exercise modalities. During some exercise modalities (e.g., high-intensity interval exercise), blood metabolites and hormonal levels change in short periods of time. In the present study, we describe a method to catheterize the antecubital vein, which allows the collection of several blood samples during exercise. Insulin and venous lactate concentrations were measured during high-intensity exercise by the application of the described method. The exercise consisted of three 30 s bouts of high-intensity exercise separated by 4 min of recovery. After the last recovery period, a Wingate test was performed. Blood samples from the antecubital vein were obtained before and after each 30 s bout and before and after the Wingate test. As a result, it was possible to evaluate the plasma insulin and venous blood lactate variations during the exercise.

Active Recovery between Interval Bouts Reduces Blood Lactate While Improving Subsequent Exercise Performance in Trained Men

This study aimed to examine the blood lactate and blood pH kinetics during high-intensity interval training. Seventeen well-trained athletes exercised on two different occasions. Exercises consisted of three 30 s bouts at a constant intensity (90% of peak power) with 4 min recovery between bouts followed by a Wingate test (WT). The recoveries were either active recovery (at 60% of the lactate threshold intensity) or passive recovery (resting at sitting position). During the exercise, blood samples were taken to determine blood gasses, blood lactate, and blood pH, and peak and average power were calculated for the WT. When performing the active recovery trials, blood pH was significantly higher (p < 0.01) and blood lactate was significantly lower (p < 0.01) compared with the passive recovery trials. WT performance was significantly higher in the active recovery trials: peak power was 671 ± 88 and 715 ± 108 watts, and average power was 510 ± 70 and 548 ± 73 watts (passive and active respectively; p < 0.01). However, no statistically significant correlations were found between the increased pH and the increased performance in the active recovery trials. These results suggest that active recovery performed during high-intensity interval exercise favors the performance in a following WT. Moreover, the blood pH variations associated with active recovery did not explain the enhanced performance.

Effects of active recovery during interval training on plasma catecholamines and insulin.

BACKGROUNDː Active recovery has been used as a method to accelerate the recovery during intense exercise. It also has been shown to improve performance in subsequent exercises, but little is known about its acute effects on the hormonal and metabolic profile. The aim of this research was to study the effects of active recovery on plasma catecholamines and plasma insulin during a high-intensity interval exercise. METHODSː Seven subjects performed two high-intensity interval training protocols which consisted of three 30-second high-intensity bouts (constant intensity), separated by a recovery of 4 minutes. The recovery was either active recovery or passive recovery. During the main test blood samples were collected and plasma insulin, plasma catecholamines and blood lactate were determined. Furthermore, respiratory gasses were also measured. RESULTSː Plasma insulin and blood lactate were significantly higher in the passive recovery trial, while plasma adrenaline was higher in the active recovery. Additionally, VO2 and VCO2 were significantly more increased during the active recovery trials. CONCLUSIONSː These results suggest that active recovery affects the hormonal and metabolic responses to high-intensity interval exercise. Active recovery produces a hormonal environment which may favor lipolysis and oxidative metabolism, while passive recovery may be favoring glycolysis.