Examining the association between speed and myoelectric activity: Time-based differences and muscle group balance.

The purpose of this study is to investigate the relationship between speed and myoelectric activity, measured during an incremental 25m shuttle running test, exploring the time-based variations and assessing muscle group balance within the context of this association. Twelve male young soccer players (n = 12) aged 18±1.2 years, with an average body mass of 68.4±5.8kg and average body height of 1.72±0.08m, from a professional Italian youth team (Italian "Primavera"), volunteered as participants for this study. The speed of each player during testing was measured using GPS technology, sampling at 50Hz. Myoelectrical activities of the gluteus, hamstrings, and quadriceps muscles were recorded through wearable sEMG devices, sampled at 100Hz. To ensure alignment of the sampling frequencies, the sEMG data was resampled to 50Hz, matching the GPS data sampling rate. This allowed for direct comparison and analysis of the data obtained from both measurement systems. The collected data were then analyzed to determine the relationship between the investigated variables and any potential differences associated with different sides of the body. The results revealed a robust correlation (r2≈0.97) between the speed of the participants (m·s-1) and their myoelectrical activity (µV) during the test. Factorial ANOVA 2x11 showed no significant differences between the sides of the analyzed muscles (p>0.05). The interpolation lines generated by the association of speed and sEMG exhibit very similar angular coefficients (0.9 to 0.12) in all six measurements obtained from electromyography of the three investigated muscle groups on each side of the body. In conclusion, the concurrent validity between the two instruments in this study indicates that GPS and sEMG are valid and consistent in estimating external load and internal load during incremental shuttle running.

Acute Effects of Whole-Body Electrostimulation Combined with Stretching on Lower Back Pain.

Data from recent studies suggest that whole-body electromyostimulation (WB-EMS) is a time-effective and tailored intervention for chronic lower back pain (CLBP). The aim of this non-randomized controlled study was to compare the efficacy of a WB-EMS training and the association between WB-EMS specific training with passive stretching (Well Back System, [WBS]) on CLBP. Forty patients with CLBP, 43-81 years old, were assigned to one of the two groups: WB-EMS (n=20) and WB-EMS+WBS (n=20). Both groups completed 12 sessions (8 weeks) of the WB-EMS protocol (2×20 minutes/week). The second group performed core-specific exercises with WB-EMS plus 6 extra stretching sessions (30 minutes each). Primary study endpoints were based on changes on the visual analogue scale (VAS) and changes on the Oswestry Low Back Disability Questionnaire (ODI). Secondary study endpoints were percentage changes of maximum trunk flexion (Sit & Reach, [SR]) and changes in consumption of painkillers. Both interventions significantly improved VAS, ODI, and SR values (p range: 0.04;<0.001). However, the change of VAS (-46% vs. -17%, p<0.001), ODI (-53% vs. -17%, p<0.001), and SR (+ 7 vs.+3 cm, p=0.001) were significantly higher in the WB-EMS+WBS group compared to the WB-EMS group. The working method with WB-EMS+WBS can be a joint-friendly, individualized form to decrease CLBP.

Whole-body Electromyostimulation plus Caloric Restriction in Metabolic Syndrome.

We investigated early effects of Whole-Body Electromyostimulation added to hypocaloric diet on metabolic syndrome features in sedentary middle-aged individuals. We randomly assigned 25 patients to Whole-Body Electromyostimulation plus caloric restriction or caloric restriction alone for 26 weeks. Anthropometrics, blood pressure, fasting glucose and insulin, HOMA-IR, glycated hemoglobin, lipids, uric acid, creatinphosphokynase, C-reactive protein were assessed. Body composition was evaluated with direct-segmental, multi-frequency Bioelectrical Impedance Analysis. Both groups lost approximately 10% of weight, with similar effects on waist circumference and fat mass. Change in free-fat mass was significantly different between groups (caloric restriction -1.5±0.2 vs. Whole-Body Electromyostimulation plus caloric restriction +1.1±0.4 kg, p=0.03). Whole-Body Electromyostimulation plus caloric restriction group experienced greater percent reductions in insulin (-45.5±4.4 vs. -28.2±3.6%, p=0.002), HOMA-IR (-51.3±3.2 vs. -25.1±1.8%, p=0.001), triglycerides (-22.5±2.9 vs. -4.1±1.6%, p=0.004) and triglycerides/HDL (p=0.028). Subjects trained with Whole-Body Electromyostimulation had also significant improvement in systolic pressure (138±4 vs. 126±7 mmHg, p=0.038). No discontinuations for adverse events occurred. In middle-aged sedentary subjects with the metabolic syndrome, Whole-Body Electromyostimulation with caloric restriction for 26 weeks can improve insulin-resistance and lipid profile compared to diet alone. Further studies are needed to ascertain long-term efficacy and feasibility of this approach in individuals with the metabolic syndrome.

Effects of Two Modalities of Whole-body Electrostimulation Programs and Resistance Circuit Training on Strength and Power.

The main purpose of this study was to compare the effects on strength and muscle power of a training program based on two different modalities of whole-body electrostimulation (WB-EMS) with respect to a resistance-training program aimed at improving dynamic strength. Twenty-two subjects participated in this study: Thirteen male (age 25.2±2.8 years; height 1.78±0.1 m; body mass 72.8±6.4 kg; body fat 11.6±2.3%) and nine female (age 28.2±3.5 years; height 1.63±0.05 m; body mass 56.8±7.6 kg; body fat 19.1±4.7%). Participants were randomly assigned to three groups that underwent three different 6-week training programs: two modalities of WB-EMS, based on different electrical parameters (experimental), and circuit training with overloads (control). Force-velocity curves were calculated for each participant before and after treatment. All groups improved their level of strength and muscle power (paired sample t-Test, p<0.01; d>1) with a similar magnitude. No significant differences were observed between groups (two-way 2×3 Anova, p>0.05) at the end of the experimentation. This study suggests that WB-EMS might be considered as a valid and faster alternative - or an important complementary procedure - to a traditional overload-based resistance-training program for the development of the DS.

Match analysis and temporal patterns of fatigue in rugby sevens.

Rugby sevens is a rapidly growing sport. Match analysis is increasingly being used by sport scientists and coaches to improve the understanding of the physical demands of this sport. This study investigated the physical and physiological demands of elite men's rugby sevens, with special reference to the temporal patterns of fatigue during match play. Nine players, 4 backs and 5 forwards (age 25.1 ± 3.1 years) participated during 2 "Roma 7" international tournaments (2010 and 2011). All the players were at the professional level in the highest Italian rugby union, and 5 of these players also competed at the international level. During the matches (n = 15), the players were filmed to assess game performance. Global positioning system, heart rate (HR), and blood lactate (BLa) concentration data were measured and analyzed. The mean total distance covered throughout matches was 1,221 ± 118 m (first half = 643 ± 70 m and second half = 578 ± 77 m; with a decrease of 11.2%, p > 0.05, Effect Size [ES] = 0.29). The players achieved 88.3 ± 4.2 and 87.7 ± 3.4% of the HRmax during the first and second halves, respectively. The BLa for the first and second halves was 3.9 ± 0.9 and 11.2 ± 1.4 mmol·L, respectively. The decreases in performance occurred consistently in the final 3 minutes of the matches (-40.5% in the distance covered per minute). The difference found in relation to the playing position, although not statistically significant (p = 0.11), showed a large ES (η = 0.20), suggesting possible practical implications. These results demonstrate that rugby sevens is a demanding sport that places stress on both the anaerobic glycolytic and aerobic oxidative energy systems. Strength and conditioning programs designed to train these energy pathways may prevent fatigue-induced reductions in physical performance.

Influence of the number of trials and the exercise to rest ratio in repeated sprint ability, with changes of direction and orientation.

The purpose of this investigation was to determine if there were different trends in physical fatigue observed in 3 different sets, of 7 trials each, in repeated sprint training, performed in 3 different modes: straight sprinting over 30 m, shuttle sprinting over 15 + 15 m, and sprinting over 30 m with changes of direction. Recovery time among trials in the sets was administered according to the 1:5 exercise to rest ratio. The sets were performed on 3 different days, with at least 48 hours between each set. The study involved 17 trained male soccer players (height, 177.33 ± 6.21 cm; body mass, 71.63 ± 9.58 kg; body mass index, 23 ± 2.39 kg·m; age, 21.94 ± 3.58 years). To compare the different values of the time recorded, an index of fatigue was used. Significant differences among trials within each set (repeated measures analysis of variance; p < 0.05) and between the sets (factorial analysis of variance; p < 0.001) were found. Significant correlations between each test and countermovement jump and stiffness values recorded pre exercise were found (p < 0.05). Significant differences between countermovement jump and stiffness values recorded pre and post exercise were also found (p < 0.05). This study suggests that training sessions aimed at increasing the capacity of repeated sprint ability in nonlinear and multidirectional sprints (shuttle and change of direction), which might imply a different number of trials within the set or different exercise to rest ratios from the ones usually adopted for straight sprinting, to induce similar trends of fatigue. As practical applications, the estimated numbers of necessary trials in the different sets and the possible exercise to rest ratios, resulting from mathematical modeling, are provided for each investigated sprinting mode.