High versus Low-Intensity Resistance Training on Bone Mineral Density and Content Acquisition by Postmenopausal Women with Osteopenia: A Randomized Controlled Trial.

Background: The menopause stage in women reduces estrogen levels and bone indicators. This study compared the effects of high-intensity resistance training (HIRT) and low-intensity resistance training (LIRT) on bone mineral density (BMD) and bone mineral content (BMC), T-score, and Z-score in postmenopausal women with osteopenia. Methods: A randomized controlled trial was conducted among 45 postmenopausal women, aged 50 to 60, who were randomly assigned into 3 parallel groups (n = 15 in each). The exercise program was performed by the interventional groups-the HIRT and LIRT groups-at 4 different intensities, 3 times a week for 24 weeks: 8 repetitions at 80% of 1 repetition maximum and 16 repetitions at 40% of 1 repetition maximum. The evaluated areas (BMD, BMC, T-score, and Z-score) included the lumbar spine (LS) and the femur neck (FN) using a DEXA machine. One-way analysis of covariance and Bonferroni's post hoc tests were used for data analysis. Results: The results indicated significant differences in BMD, BMC, T-scores, and Z-scores between the means of the LS and the FN in all groups. In addition, significant differences were revealed in the BMC of the LS, the BMD, T-scores (P < 0.001), Z-scores (P = 0.001), and in the BMC of the FN (P < 0.001), the BMD (P = 0.001), T-scores, and Z-scores (P < 0.001), respectively. In addition, the HIRT group's bone indices were considerably greater than those of the LIRT group (P < 0.00). Nonetheless, LIRT was significantly greater than that of the control group (P > 0.00). Conclusion: According to the current findings, HIRT seems to be the most effective training program compared with LIRT for bone indicators improvement in the femur neck and the lumbar spine among postmenopausal women with osteopenia.

Isokinetic muscle strength cannot be related to the odds ratio of musculoskeletal injuries in young elite wrestlers.

BACKGROUND: Wrestling is considered one of the oldest sports in the world. There is a high rate of injuries in Wrestling. To prevent injuries, it is necessary to identify the risk factors. Despite the functional importance of strength in wrestling, few studies have investigated the relationship between isokinetic strength and the rate of injuries in the sport. OBJECTIVES: The objective of the present study was to investigate the relationship between the isokinetic strength of elite wrestlers and the rate of injuries prospectively. METHOD: A total of 72 young wrestlers with at least 2 years of experience in the Tehran Wrestling Premier League participated in this study. Before the start of the competition season, the isokinetic strength of flexor and extensor muscles of the knee and shoulder were measured at different velocities by an isokinetic dynamometer. The injuries and training hours of these wrestlers were then recorded for nine months. RESULTS: The study results showed no significant relationship between isokinetic strength of flexor and extensor muscles of the knee or shoulder at different angular speeds of 60, 180, and 300°/s. There was neither significant between the ratio of the strength flexor/extensor for knee and/or shoulder in young elite wrestlers with injuries. CONCLUSION: Isokinetic strength of lower and upper limb muscles alone cannot predict wrestlers' injuries. Therefore, the use of these tests is not recommended to evaluate the risk of injury in this population.

Proprioception is not associated with lower extremity injuries in U21 high-level football players.

Football is a contact sport with a significant risk of injury. Although proprioception is well studied in rehabilitation, little is known about the association between proprioception and the occurrence of sport injuries. The purpose of this study was to look into the association between ankle and knee proprioception and lower extremity injuries in young football players. Seventy-three football players from the highest U-21 league in Iran volunteered to participate in this study. Before the start of the 2017-2018 competitive season, joint position sense was measured at 30°, 60° and 90° knee flexion and at 10° and 15° ankle dorsiflexion, and inversion using the Biodex Isokinetic pro 4 system. The teams' medical staff recorded football-related lower extremity injuries. We used mixed effects Cox regression models to calculate hazard ratios (HRs) with 95% CIs, acknowledging the clustered data structure. Twenty-two players (30.1%) suffered one or more lower extremity injuries during the season. None of the proprioception measures examined was significantly associated with the risk of lower extremity injuries. Based on these results of our sample, joint position sense does not seem to be associated with lower extremity injuries in young male football players.

The association between the isokinetic muscle strength and lower extremity injuries in young male football players.

BACKGROUND: Validating any screening test to predict and prevent football injuries is in need of identifying related risk factors through prospective designs. In spite of the extensive use of strength testing in football players, there are limited studies investigating the relationship between isokinetic muscle strength and injury risk in young football players. The present study aimed to evaluate the relationship between isokinetic strength and the risk of lower extremity injury among Iranian young football players. METHOD: ology: seventy three U-21 football players participated in this study. Isokinetic strength of hip, knee and ankle muscles were measured using the Isokinetic system pro 4. Injuries and exposure in training and matches were registered prospectively by club medical staff for one season. RESULTS: Significant relationships were revealed between the isokinetic strength of hip abductor and adductor muscles, and isokinetic strength ratio of hip abductor/adductor muscles at an angular speed of 30°/sec, the isokinetic strength of hip abductor muscles at 90°/sec, and isokinetic strength of knee flexor and extensor muscles at 60°/sec and knee flexor/extensor strength ratio at angular velocities of 60°/sec with the injury occurrence among football players. CONCLUSION: lower extremity isokinetic strength indices are associated with injuries in young male football players.

Mild aerobic training with blood flow restriction increases the hypertrophy index and MuSK in both slow and fast muscles of old rats: Role of PGC-1α.

AIMS: Existing evidence emphasize the role of mitochondrial dysfunction in sarcopenia which is revealed as loss of skeletal muscle mass and neuromuscular junction remodeling. We assessed the effect of low-intensity aerobic training along with blood flow restriction on muscle hypertrophy index, muscle-specific kinase (MuSK), a pivotal protein of the neuromuscular junction and Peroxisome proliferator-activated receptor gamma co-activator 1-alpha (PGC-1α) in aged male rats. MAIN METHODS: Animals groups were control (CTL), sham (Sh), leg blood flow restriction (BFR), exercise (Ex), sham + exercise (Sh + Ex), and BFR plus exercise (BFR + Ex) groups. The exercise groups were trained with low intensity exercise for 10 weeks. 48 h after the last training session, animals were sacrificed under anesthesia. Soleus and EDL muscles were isolated, hypertrophy index was estimated and MuSK and PGC-1α were measured by western blot method. KEY FINDINGS: Hypertrophy index enhanced in soleus and Extensor digitorum longus (EDL) muscles of BFR + Ex group (P < 0.01 versus CTL and Sh groups, and P < 0.001 versus other groups). The MuSK protein of soleus and EDL muscles increased in BFR + Ex group (P < 0.01 and P < 0.001, respectively) in comparison with CTL and Sh groups. In BFR + Ex group, the PGC-1α protein increased in both soleus and EDL (P < 0.001 compared to other groups). Also the PGC-1α of soleus muscle was higher in Ex and Sh + Ex groups versus CTL and Sh groups (P < 0.05). SIGNIFICANCE: Findings suggest that low endurance exercise plus BFR improves the MuSK and hypertrophy index of both slow and fast muscles of elderly rats probably through the rise of PGC-1α expression.

Long-term Low-Intensity Endurance Exercise along with Blood-Flow Restriction Improves Muscle Mass and Neuromuscular Junction Compartments in Old Rats.

BACKGROUND: During the aging process, muscle atrophy and neuromuscular junction remodeling are inevitable. The present study aimed to clarify whether low-intensity aerobic exercise along with limb blood-flow restriction (BFR) could improve aging-induced muscle atrophy and nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction. METHODS: Forty-eight male Wistar rats, aged 23-24 months, were randomly divided into control, sham (Sh: subjected to surgery without BFR), BFR (subjected to BFR), exercise (Ex: subjected to 10 weeks of low-intensity exercise), Sh+Ex, and BFR+Ex groups. Forty-eight hours after the last training session, the animals were sacrificed and their soleus and extensor digitorum longus (EDL) muscles were removed. The hypertrophy index was calculated, and molecular parameters were measured using western blotting. Statistical analysis was done with ANOVA using SPSS (version 20), with a P<0.05 as the level of significance. RESULTS: The control and Sh groups showed weight gain (P=0.001), whereas the Ex, Sh+Ex, and BFR+Ex groups had significant weight loss (P<0.001). The hypertrophy index of the soleus was significantly higher in the BFR+Ex group than in the control, Sh, and BFR groups (P<0.001). BFR+Ex induced significant hypertrophic effects on the EDL (P<0.001 vs. the control, Sh, Ex, and Sh+Ex groups, and P=0.006 vs. the BFR group). BFR+Ex also increased nAChRs in the soleus (P=0.02 vs. the control and Sh groups) and the EDL (P=0.008 vs. the control and Sh groups). CONCLUSION: BFR plus mild exercise is a safe method with potential beneficial effects in protecting and augmenting muscle mass and nAChR clustering at the neuromuscular junction in old rats.

Effects of sprint interval and continuous endurance training on serum levels of inflammatory biomarkers.

Chronic and inflammatory diseases are major causes of mortality. Although the anti-inflammatory effects of exercise have been confirmed, but the effect of different types of exercise on inflammatory markers is different. The aim of this study is comparing the effects of two types of sprint interval (SIT) and continuous endurance (CET) training on inflammatory markers. Sixteen students who had recreational activities participated in this study and were randomly assigned to one of the two protocols. The SIT protocol consisted of four to six 30-s "all-out" Wingate tests separated by 4 minutes of recovery and The CET protocol included 90-120 minutes of cycling at 65% Vo2max. The two protocols were performed 3 days per week and for two weeks. In each group, two blood samples were collected before and 2 days (24 and 48 hrs) after the training. Results showed that there was no significant difference between the two training protocols on all measured parameters (p>0.05). The results of present study showed that the SIT and CET have identical effects on inflammatory markers.