The authors have nothing to disclose. All research activities were funded by the Academy of Physical Education, Katowice, Poland.

No abstract

Although the total “Timed-Up-and Go” test (TUG) performance time can characterize an age-related decline of general mobility, this result alone doesn’t give any detailed information about the test subtasks. The primary objective of the study was to identify in nursing home women a variable extracted from instrumented TUG (iTUG) that is the best predictor of age. The secondary objective was to assess whether this variable is associated with the results of the isometric knee extension peak torque (IKEPT); lower limb strength measured by the 30-s chair stand test (30sCST), and walking capacity measured by the 6-min walk test (6MWT). Twenty-six women (mean ± SD: age—85.8 ± 3.6 years; body weight—59.4 ± 12.3 kg; body height—151.0 ± 7.3 cm; BMI—26.0 ± 4.9 kg/m2) performed iTUG (while wearing a body-fixed inertial sensor) and functional tests. Total iTUG performance time significantly correlated with age (r = 0.484; p < 0.05), 30sCST (r = −0.593; p < 0.01), and 6MWT (r = −0.747; p < 0.001) but not with absolute nor relative IKEPT (p > 0.05). Additionally, the subjects’ age correlated with 30sCST (r = −0.422; p < 0.05), 6MWT (r = −0.482; p < 0.05), IKEPT (r = −0.392; p < 0.05) and IKEPT/FFM (r = −0.407; p < 0.05). Five out of 16 analyzed iTUG variables were significantly related to age, and multiple regression analysis showed the best correlation with the sit-to-stand vertical acceleration range (STSVAR) (r2 = 0.430; SEE = 3.041; β = −0.544 ± 0.245; B = −1.204 ± 0.543; p < 0.05). Moreover, STSVAR was significantly associated with %Fat (r = 0.415; p < 0.05), 30sCST (r = 0.519; p < 0.01), 6MWT (r = 0.585; p < 0.01) but not with absolute nor relative IKEPT (p > 0.05). The obtained results suggest that in the oldest old group of nursing home women an age-related decline in TUG performance is mainly associated with a reduction of “explosive” strength of lower limb muscles.

No abstract

The aim of this study was to find out whether a low-carbohydrate diet (L-CHO) affects: (1) the capacity for all-out anaerobic exercise, and (2) hormonal and metabolic responses to this type of exercise. To this purpose, eight healthy subjects underwent a 30-s bicycle Wingate test preceded by either 3 days of a controlled mixed diet (130 kJ/kg of body mass daily, 50% carbohydrate, 30% fat, 20% protein) or 3 days of an isoenergetic L-CHO diet (up to 5% carbohydrate, 50% fat, 45% protein) in a randomized order. Before and during 1 h after the exercise venous blood samples were taken for measurement of blood lactate (LA), beta-hydroxybutyrate (beta-HB), glucose, adrenaline (A), noradrenaline (NA) and insulin levels. Oxygen consumption (VO2) was also determined. It was found that the L-CHO diet diminished the mean power output during the 30-s exercise bout [533 (7) W vs 581 (7) W, P < 0.05] without changing the maximal power attained during the first or second 5-s interval of the exercise. In comparison with the data obtained after the consumption of a mixed diet, after the consumption of a L-CHO diet resting plasma concentrations of beta-HB [2.38 (0.18) vs 0.23 (0.01) mmol x l(-1), P < 0.001] and NA [4.81 (0.68) vs 2.2 (0.31) nmol x l(-1), P < 0.05] were higher, while glucose [4.6 (0.1) vs 5.7 (0.2) mmol x l(-1), P < 0.05] and insulin concentrations [11.9 (0.9) vs 21.8 (1.8) mU x l(-1)] were lower. The 1-h post-exercise excess of VO2 [9.1 (0.25) vs 10.6 (0.25) 1, P < 0.05], and blood LA measured 3 min after the exercise [9.5 (0.4) vs 10.6 (0.5) mmol x l(-1), P < 0.05] were lower following the L-CHO treatment, whilst plasma NA and A concentrations reached higher values [2.24 (0.40) vs 1.21 (0.13) nmol x l(-1) and 14.30 (1.41) vs 8.20 (1.31) nmol x l(-1), P < 0.01, respectively]. In subjects on the L-CHO diet, the plasma beta-HB concentration decreased quickly after exercise, attaining approximately 30% of the pre-exercise value within 60 min, while insulin and glucose levels were elevated. The main conclusions of this study are: (1) a L-CHO diet is detrimental to anaerobic work capacity, possibly because of a reduced muscle glycogen store and decreased rate of glycolysis; (2) reduced carbohydrate intake for 3 days enhances activity of the sympathoadrenal system at rest and after exercise.

Skeletal muscle mitochondrial capacity (mito), tissue blood flow (BF) capacity, and oxygen exchange capacity (e.g., DO2) appear to be well matched. The different skeletal muscle fiber types and muscle remodeled, due to inactivity (e.g., related to aging or disease) or exercise training, exhibit widely differing aerobic capacities (VO2max). Yet, there are remarkably coordinated alterations in these 3 parameters in each of these conditions. With such a balance, there is likely shared control among these parameters in limiting VO2max of muscle, although this is a matter of considerable debate. The reduction in aerobic capacity in elderly can be improved by submaximal aerobic exercise training; this is related to increases in muscle mitochondria concentration and capillarity, but probably not BF capacity, as this is limited by central cardiovascular function. Thus, exercise-induced biochemical adaptations and angiogenesis occur in the elderly. The increase in muscle capillarity likely contributes to the increased oxygen exchange capacity, typical of endurance type training. The increase in [mito] appears essential to realize the increased in muscle VO2max with training and amplifies the rate-limiting influence of the muscles oxygen exchange capacity. Further, vascular remodeling induced by exercise in the elderly could be effective at improving flow capacity, if limited by peripheral obstruction. Thus, the limits to aerobic function specific to aged muscle appear most influenced by inactivity, whereas central cardiovascular changes impact whole body performance. Some may consider the aged myocyte as a small, inactive, normal myocyte in need of activity!

The purpose of this study was to discover whether severe dietary carbohydrate (CHO) restriction modifies the relationship between exercise intensity and hormonal responses to exercise. Changes in the plasma adrenaline (A), noradrenaline (NA), growth hormone (hGH), testosterone (T), and blood lactate (LA) during an incremental exercise performed until volitional exhaustion were determined in 8 physically active volunteers after 3 days on low CHO (< 5% of energy content; L-CHO) and isocaloric mixed (M) diets. Following L-CHO diet, the basal plasma A, NA, and hGH concentrations were increased, whilst T and LA levels were decreased. During exercise all the hormones increased exponentially, with thresholds close to that of LA. Neither the magnitude nor the pattern of the hormonal changes were affected by L-CHO diet except the NA threshold, which was lowered. Blood LA response to exercise was diminished and LA threshold was shifted towards higher loads by L-CHO diet. It is concluded that restriction of CHO intake (a) does not affect the pattern of changes in plasma A, hGH, and T concentrations during graded exercise but lowers NA threshold, indicating increased sensitivity of the sympathetic nervous system to exercise stimulus; (b) alters the basal and exercise levels of circulating hormones, which may have an impact on the balance between anabolic and catabolic processes and subsequently influence the effectiveness of training.

No abstract