Lifelong physical exercise delays age-associated skeletal muscle decline.

Aging is usually accompanied by a significant reduction in muscle mass and force. To determine the relative contribution of inactivity and aging per se to this decay, we compared muscle function and structure in (a) male participants belonging to a group of well-trained seniors (average of 70 years) who exercised regularly in their previous 30 years and (b) age-matched healthy sedentary seniors with (c) active young men (average of 27 years). The results collected show that relative to their sedentary cohorts, muscle from senior sportsmen have: (a) greater maximal isometric force and function, (b) better preserved fiber morphology and ultrastructure of intracellular organelles involved in Ca(2+) handling and ATP production, (c) preserved muscle fibers size resulting from fiber rescue by reinnervation, and (d) lowered expression of genes related to autophagy and reactive oxygen species detoxification. All together, our results indicate that: (a) skeletal muscle of senior sportsmen is actually more similar to that of adults than to that of age-matched sedentaries and (b) signaling pathways controlling muscle mass and metabolism are differently modulated in senior sportsmen to guarantee maintenance of skeletal muscle structure, function, bioenergetic characteristics, and phenotype. Thus, regular physical activity is a good strategy to attenuate age-related general decay of muscle structure and function (ClinicalTrials.gov: NCT01679977).

Muscle strength, resting muscle tone and EMG activation in untrained men: interaction effect of time of day and test order-related confounding factors.

AIM: This article was designed to study an interaction effect of time of day and test order-related confounding factors on daily variation in maximum muscle strength and power. METHODS: Seventeen untrained men were randomized into four groups and measured at four time points (08:00 a.m., 12:00 a.m., 04:00 p.m. and 08:00 p.m.) throughout one or two days. Each groups started at different time of day in a counter-balanced order. Peak force and myoelectrical activity (EMG) of vastus medialis, vastus lateralis and biceps femoris muscles during bilateral isometric leg extension and power output during explosive dynamic leg extension was measured. Computerized muscle tonometer was used to assess resting muscle tone. RESULTS: Resting muscle tone did not change significantly regardless of time of day or test order. In contrast, time-of-day effect was found in force and EMG during isometric leg extension and in power output; all variables were significantly lower in the morning compared to the individual best performance/highest value achieved at any time point. In addition, the above variables were also affected by test order. Regardless of time of day, isometric force and EMG were typically highest during the first test session, while the dynamic power output gradually improved with test order. CONCLUSION: Daily variation in maximum voluntary strength and power performance could be detected despite the test order-related confounding factors.

Effects of strength training on work capacity and parasympathetic heart rate modulation during exercise in physically inactive men.

This study was designed to assess the effects of strength training on work capacity and parasympathetic heart rate modulation during exercise in physically inactive men. Seventy-four men aged 20-45 were randomly assigned to training (n=52) and control (n=22) groups. Training groups underwent 10-weeks of progressive strength training. Body composition, one-repetition maximum half-squat and maximal oxygen uptake were measured before and after the intervention. Respiratory gases, heart rate and blood lactate were recorded during a VO2max test on a cycle ergometer. Parasympathetic heart rate modulation was analyzed based on the standard deviation of instantaneous beat-to-beat R-R interval variability (SD1) and its normalized unit (SD1n). Muscle strength and lean body mass increased in the training group. Compared to the control group, time to exhaustion increased significantly in the training group (p<0.05). SD1 and SD1n were elevated in the training group at submaximal exercise intensities (100 W, p<0.05). Blood lactate decreased at submaximal intensities when compared to the control group. Strength training increased exercise capacity, and improved vagal modulation of heart rate at submaximal exercise intensities. These changes may have favourable cardiovascular health implications for sedentary men during normal daily activities.

Diurnal variation in maximal and submaximal strength, power and neural activation of leg extensors in men: multiple sampling across two consecutive days.

This study aimed to compare day-to-day repeatability of diurnal variation in strength and power. Thirty-two men were measured at four time points (07 : 00 - 08 : 00, 12 : 00 - 13 : 00, 17 : 00 - 18 : 00, and 20 : 30 - 21 : 30 h) throughout two consecutive days (day 1 and day 2). Power during loaded squat jumps, torque and EMG during maximal (MVC) and submaximal (MVC40) voluntary isometric knee extension contractions were measured. The EMG/torque ratio during MVC and MVC40 was calculated to evaluate neuromuscular efficiency. A significant time-of-day effect with repeatable diurnal patterns was found in power. In MVC, a significant time-of-day effect was present on day 2, whereas day 1 showed a typical but nonsignificant diurnal pattern. EMG and antagonist co-activation during MVC remained statistically unaltered, whereas neuromuscular efficiency improved from day 1 to day 2. A similar trend was observed in MVC40 neuromuscular efficiency with significant time-of-day and day-to-day effects. Unaltered agonist and antagonist activity during MVC suggests that modification at the muscular level was the primary source for the diurnal variation in peak torque. A learning effect seemed to affect data in MVC40. In conclusion, the second consecutive test day showed typical diurnal variation in both maximum strength and power with no day-to-day effect of cumulative fatigue.

Seasonal variation of red blood cell variables in physically inactive men: effects of strength training.

The purpose of this study was to investigate if strength training affects red blood cell variables in physically inactive men when taking into account seasonal variations. Seventy-four men aged 20-45 were randomly assigned to training (n = 52) and control (n = 22) groups. Training group underwent 20-week progressive strength training. Body composition and maximal voluntary contraction (MVC) during knee extension were measured before and after intervention. Fasting blood samples were analysed for haematocrit (Hct), count of red blood cells (RBC), haemoglobin (Hb), mean cell haemoglobin concentration (MCHC), and mean cell volume (MCV) at baseline, 10-week and 20-week follow-up. MVC and lean body mass increased in the training group. Hct, Hb and MCHC showed seasonal variation in the control group. The training group increased their Hct from 44.7 +/- 2.6 % to 45.4 +/- 2.5 % (p = 0.026) while the control group decreased their Hct from 44.3 +/- 2.2 % to 43.1 +/- 2.6 % (p = 0.037) after 20-week intervention. By contrast to the control group, the training group increased their Hct (p = 0.001), RBC (p = 0.005) and decreased their MCHC (p < 0.001) from 10-week to 20-week follow-up. We concluded that strength training could affect seasonal variation patterns of red cell variables. Unlike "sport anaemia" induced by endurance training, 20-week strength training elevated Hct.

Complement consumption in fresh blood sera by double culture of Paramecium caudatum and Aerobacter cloacae compared with survival and stage of disease in some malignant tumors in man.

Using the complement consumption test by double culture of Paramecium caudatum and Aerobacter cloacae (DPA) as antigen we examined blood sera and compared survival rates and stage of disease in 124 patients with carcinoma of cervix uteri, corpus uteri, ovaries and breast. The evidence suggests that bacteria Aerobacter cloacae constitute the proper antigenically effective substances of DPA. The intensity of reaction and therapy the relative titres of antibodies detected by the test were expressed by the amount of complement consumed in the reaction and designated by the abbreviation "NMHD", i. e. number of minimum haemolytic doses of complement fixed by antigen in the reaction. Patients with NMHD above 8 (i. e. with an intensive reaction corresponding to a high level of antibodies) exhibited partly higher three-year survival rates -- starting from the time of diagnosis, partly more often the clinical stages of disease I or II as compared with patients with NMHD below 4. The best survival rates were found in patients with NMHD above 8 and clinical stage I or II. NMHD values in patients with the initial period of disease and in healthy women did not differ substantially.