BackgroundSeveral studies have demonstrated the positive effects of physical activity on skeletal muscle mass and muscle strength in women with osteoporosis. However, the impact of Nordic walking training on sarcopenia-related parameters in women with low bone mass remains unknown. Therefore, the purpose of this study was to evaluate the impact of 12 weeks of Nordic walking training on skeletal muscle index, muscle strength, functional mobility, and functional performance in women with low bone mass.Materials and methodsThe participants were 45 women, aged 63–79 years, with osteopenia or osteoporosis. The subjects were randomly assigned either to an experimental group (12 weeks of Nordic walking training, three times a week) or to a control group. Skeletal muscle mass and other body composition factors were measured with octapolar bioimpedance InBody 720 analyser. Knee extensor and flexor isometric muscle strength were measured using Biodex System 4 Pro™ dynamometers. This study also used a SAEHAN Digital Hand Dynamometer to measure handgrip muscle strength. The timed up-and-go test was used to measure functional mobility, and the 6-minute walk test was used to measure functional performance.ResultsShort-term Nordic walking training induced a significant increase in skeletal muscle mass (P=0.007), skeletal muscle index (P=0.007), strength index of the knee extensor (P=0.016), flexor (P<0.001), functional mobility (P<0.001), and functional performance (P<0.001) and a significant decrease in body mass (P=0<006), body mass index (P<0.001), and percent body fat (P<0.001) in participants. Regarding handgrip muscle strength, no improvement was registered (P=0.315). No significant changes in any of the analyzed parameters were observed in the control group.ConclusionOverall, short-term Nordic walking training induces positive changes in knee muscle strength and functional performance in women with low bone mass. This finding could be applied in clinical practice for intervention programs in women with osteopenia and osteoporosis.

The aim of the study was to define the relationship between maximal power of lower limbs, the biomechanics of the forward handspring vault and the score received during a gymnastics competition. The research involved 42 gymnasts aged 9-11 years competing in the Poland’s Junior Championships. The study consisted of three stages: first -estimating the level of indicators of maximal power of lower limbs tested on a force plate during the countermovement jump; second - estimating the level of biomechanical indicators of the front handspring vault. For both mentioned groups of indicators and the score received by gymnasts during the vault, linear correlation analyses were made. The last stage consisted of conducting multiple regression analysis in order to predict the performance level of the front handspring vault. Results showed a positive correlation (0.401, p < 0.05) of lower limbs’ maximal power (1400 ± 502 W) with the judges’ score for the front handstand vault (13.38 ± 1.02 points). However, the highest significant (p < 0.001) correlation with the judges’ score was revealed in the angle of the hip joint in the second phase of the flight (196.00 ± 16.64°) and the contact time of hands with the vault surface (0.264 ± 0.118 s), where correlation coefficients were: -0.671 and -0.634, respectively. In conclusion, the angles of the hip joint in the second phase of the flight and when the hands touched the vault surface proved to be the most important indicators for the received score.

No abstract

This study aimed to analyze acute changes in the muscle mechanical properties of the triceps brachii long head after bench press exercise performed at different external loads and with different intensities of effort along with power performance. Ten resistance-trained males (age: 27.7 ± 3.7 yr, body mass: 90.1 ± 17.1 kg, height: 184 ± 4 cm; experience in resistance training: 5.8 ± 2.6 yr, relative one-repetition maximum (1RM) in the bench press: 1.23 ± 0.22 kg/body mass) performed two different testing conditions in a randomized order. During the experimental session, participants performed four successive sets of two repetitions of the bench press exercise at: 50, 70, and 90% 1RM, respectively, followed by a set at 70% 1RM performed until failure, with a 4 min rest interval between each set. Immediately before and after each set, muscle mechanical properties of the dominant limb triceps brachii long head were assessed via a Myoton device. To determine fatigue, peak and average barbell velocity were measured at 70% 1RM and at 70% 1RM until failure (only first and second repetition). In the control condition, only muscle mechanical properties at the same time points after the warm-up were assessed. The intraclass correlation coefficients indicated “poor” to “excellent” reliability for decrement, relaxation time, and creep. Therefore, these variables were excluded from further analysis. Three-way ANOVAs (2 groups × 2 times × 4 loads) indicated a statistically significant group × time interaction for muscle tone (p = 0.008). Post hoc tests revealed a statistically significant increase in muscle tone after 70% 1RM (p = 0.034; ES = 0.32) and 90% 1RM (p = 0.011; ES = 0.56). No significant changes were found for stiffness. The t-tests indicated a significant decrease in peak (p = 0.001; ES = 1.02) and average barbell velocity (p = 0.008; ES = 0.8) during the first two repetitions of a set at 70% 1RM until failure in comparison to the set at 70% 1RM. The results indicate that low-volume, high-load resistance exercise immediately increases muscle tone but not stiffness. Despite no significant changes in the mechanical properties of the muscle being registered simultaneously with a decrease in barbell velocity, there was a trend of increased muscle tone. Therefore, further studies with larger samples are required to verify whether muscle tone could be a sensitive marker to detect acute muscle fatigue.

Iron is essential for physical activity due to its role in energy production pathways and oxygen transportation via hemoglobin and myoglobin. Changes in iron-related biochemical parameters after physical exercise in athletes are of substantial research interest, but molecular mechanisms such as gene expression are still rarely tested in sports. In this paper, we evaluated the mRNA levels of genes related to iron metabolism (PCBP1, PCBP2, FTL, FTH, and TFRC) in leukocytes of 24 amateur runners at four time points: before, immediately after, 3 h after, and 24 h after a marathon. We measured blood morphology as well as serum concentrations of iron, ferritin, and C-reactive protein (CRP). Our results showed significant changes in gene expression (except for TFRC), serum iron, CRP, and morphology after the marathon. However, the alterations in mRNA and protein levels occurred at different time points (immediately and 3 h post-run, respectively). The levels of circulating ferritin remained stable, whereas the number of transcripts in leukocytes differed significantly. We also showed that running pace might influence mRNA expression. Our results indicated that changes in the mRNA of genes involved in iron metabolism occurred independently of serum iron and ferritin concentrations.