Effect of whole-body vibration on postural stability in young adults with generalized joint hypermobility: A comparative study.

BACKGROUND: Whole-body vibration (WBV) is being used in rehabilitation and sport. Studies confirm its positive impact on muscle strength and power or regulating muscle hypertension. However, there are some uncertainties regarding its influence on postural stability. This issue seems particularly interesting in the case of individuals with generalized joint hypermobility (GJH), for whom proprioceptive training and muscle strengthening exercises are recommended while techniques that decrease muscle tension are not advised. OBJECTIVE: The aim of the study was to evaluate the acute effect of WBV on postural stability in adults with GJH. METHODS: 60 participants were categorized into the groups: 1) hypermobility with vibration (GJH+WBV), 2) hypermobility without vibration (GJH-WBV), 3) control group with vibration (CTRL+WBV), 4) control group without vibration (CTRL-WBV). The first and the third group completed WBV (frequency: 15 Hz and 30 Hz, amplitude 3 mm, 3 × 3 min). The second and fourth groups participated only in measurement sessions. GJH was assessed using the Beighton test. Postural stability was measured as the overall stability index (OSI) on the Biodex Balance System on the stable and unstable platform with open and closed eyes. Measurements were taken before and after WBV for two weeks. RESULTS: At a frequency of 15 Hz, a significant time effect was observed for measurements Before and After in CTRL-WBV on the stable platform with open eyes (p= 0.012) and on the unstable platform with closed eyes (p= 0.000) for the GJH+WBV and CTRL+WBV groups. There were no significant interactions (p> 0.05) between factors. At a frequency of 30 Hz, there was a significant time effect Before and After (p= 0.047) on the stable platform with open eyes, but no interaction was found between factors (p= 0.835). CONCLUSION: There is no positive acute effect of WBV on postural stability in adults with and without GJH.

Acute effects of unilateral and bilateral conditioning activity on countermovement jump, linear speed, and muscle stiffness: A randomized crossover study.

PURPOSE: Evidence directly comparing the effects of bilateral and unilateral conditioning activities is limited. Therefore, the aim of this study was to assess the acute effect of unilateral and bilateral conditioning activity on vastus lateralis stiffness, countermovement jump parameters, and 10 m sprint. METHODS: Twelve semi-professional basketball players participated in this study (age: 23 ± 4 yrs; body mass: 84.7 ± 10.6 kg; body height: 192 ± 6 cm; basketball training experience: 11 ± 4 yrs) performed four experimental sessions to compare the acute effects of bilateral, stronger-only, weaker-only lower limb or no conditioning activity on vastus lateralis stiffness, countermovement jumps variables (height; peak velocity; peak force, contraction time, countermovement depth, and modified reactive strength index and 10 m sprint time. Measurements were performed 5 minutes before and in the 5th and 10th minutes after CA. RESULTS: Bilateral conditioning activity significantly increase the countermovement jump height (p = 0.002; ES = 0.71) and the reactive strength index modified (p = 0.010; ES = 0.59). Moreover, a significantly higher peak force in the stronger than in the weaker limb was found (p<0.001) without any differences between conditions and time points (p>0.05). However, there were no significant (p>0.05) interactions and effects of conditions or time-point in the case of the other countermovement jump variables, vastus lateralis stiffness, and 10m sprint time. CONCLUSION: Unilateral and bilateral drop jumps (3 sets of 5 repetitions) did not affect the vastus lateralis stiffness and time of the 10m sprint. However, only bilateral drop jumps effectively enhanced the countermovement jump height and modified reactive strength index. Bilateral drop jumps might be a useful part of a warm-up to improve jumping performance in basketball players.

Effects of Complex Training on Jumping and Change of Direction Performance, and Post-Activation Performance Enhancement Response in Basketball Players.

Exercise order is one of the significant factors modulating training effects. Therefore, the aim of this study was to compare the effectiveness of an 8-week complex (CPX) training program utilizing intra-CPX active recovery with compound training (CMP) on bilateral and single-leg jumping performance, change of direction test time (shuttle test), and the post-activation performance enhancement (PAPE) response in a group of basketball players. Thirteen participants were performing CPX bi-weekly combined with regular pre-season basketball practice, while eleven participants were performing CMP for 8 weeks. Before and after the interventions, the following fitness tests were assessed: (i) bilateral countermovement jump, (ii) single-leg countermovement jump, (iii) shuttle run test. All tests were performed pre- and post-conditioning activity (CA-three sets of five drop jumps). The results showed a statistically significant increase in non-dominant (p = 0.019) and dominant single-leg jump relative peak power (p = 0.001), and in non-dominant single-leg jump height (p = 0.022) post-training compared to pre-training. The CA was significantly and similarly effective in eliciting a PAPE response in all tests before and after each intervention (p < 0.039; for all). However, the magnitude of improvement in CMJ and shuttle test time was trivial to small and did not reach statistical significance. Both 8 weeks of CPX and CMP training led to significant improvements in the SLJ power output of both the dominant and non-dominant limbs as well as the height of the non-dominant SLJ. Neither of the training methods had significant impacts on the magnitude of the PAPE response.

Effects of Flywheel vs. Free-Weight Squats and Split Squats on Jumping Performance and Change of Direction Speed in Soccer Players.

The objective of this study was to compare (i) The effects of a flywheel and free-weight resistance training program; and (ii) The effects of performing lateral and frontal split squats as part of a flywheel-resistance training program on jumping performance, the 5-0-5 change of direction test time, and the one-repetition maximum (1RM) back squat in soccer players. Twenty-four male amateur soccer players participated in this study and were randomly and equally assigned to one of three different test groups: forward split-squat group (FSQ); lateral split-squat group (LSQ); and free-weight training group (TRAD). Athletes in the FSQ group performed a squat and a forward split squat on a flywheel device, while those in the LSQ group performed a squat and a lateral split squat (instead of a forward split squat) on a flywheel device. Each training lasted 4 weeks. The main finding was that all training groups, such as TRAD, FSQ, and LSQ, significantly improved broad jump length (p = 0.001; effect size [ES] = 0.36), 5-0-5 COD time with a turn on the dominant limb (p = 0.038; ES = 0.49), and 1RM back squat (p = 0.001; ES = 0.4). In turn, both flywheel-resistance training groups (FSQ and LSQ) significantly improved their counter-movement jump height (p = 0.001; ES = 0.8 and p = 0.002; ES = 0.58; respectively) with no effect in the TRAD (p = 0.676; ES = 0.07) training group. Both free-weight and flywheel-resistance training lasting 4 weeks performed in-season contributed to significant improvement in 1RM back squat, broad jump performance, and 5-0-5 change of direction testing time, while flywheel-resistance training might be superior in counter-movement jump height enhancement in soccer players. Moreover, the manner in which split squats were performed was not a factor influencing the obtained results.

Acute Effects of Complex Conditioning Activities on Athletic Performance and Achilles Tendon Stiffness in Male Basketball Players.

The goal of this study was to compare the effects of a bilateral conditioning activity consisting of back squats and drop jumps with a unilateral one consisting of split squats and depth jumps to lateral hop over sequentially performed countermovement jump (CMJ), modified t-agility test (MAT), and Achilles tendon stiffness. Twenty-six basketball players participated in this study and were randomly and equally assigned to one of two different test groups: bilateral (B - CA) or unilateral (U - CA) conditioning activity group. The B - CA group completed 2 sets of 4 repetitions of back squats at 80% of one-repetition maximum (1RM), then 10 drop jumps, while the U - CA group performed 2 sets of 2 repetitions of split squats on each leg at 80%1RM, followed by 5 depth jumps to lateral hop on each leg as conditioning activity (CA) complexes. After a warm-up and 5 min before the CA the baseline Achilles tendon stiffness, CMJ, and MAT time measurement were performed. In the 6th min after the CA, all tests were re-tested in the same order. The two-way repeated measures mixed ANOVAs revealed that both B - CA and U - CA failed to produce significant improvements in CMJ and MAT performance. In addition, a significant increase in Achilles stiffness was demonstrated with both protocols (a main effect of time: p = 0.017; effect size = 0.47; medium). This study revealed that combining back squats and drop jumps, as well as split squats and depth jumps to a lateral hop, had no effect on subsequent CMJ and MAT performance in basketball players. Based on these results, it can be assumed that combinations of exercises, even if they have similar movement patterns, may cause excessive fatigue, resulting in no PAPE effect.

Effects of whole-body vibration warm-up on subsequent jumping and running performance.

The aim of this study was to examine whether acute whole-body vibration, a single bout of drop jumps, or a combination of both may enhance countermovement jump (CMJ) and would affect volitional pace 3 km running performance. Twelve healthy and recreationally active males completed 4 conditions in randomized order: (i) 5 sets of 30 s calf raises on the platform but without vibration; (ii) 5 sets of 30 s calf raises on the vibration platform with 30 s rest intervals between sets; (iii) 5 sets of 6 drop jump with a 30 s rest interval between sets; (iv) 5 sets of 30 s calf raises on the vibration platform followed by 6 drop jumps with a 30 s rest interval between sets. Before, 3-min after, and immediately after a 3 km run each participant performed CMJ. No significant difference between conditions (p = 0.327) for the 3 km time trial was found. Whereas CMJ height and relative peak power were significantly improved in post-3 km run than at baseline (p < 0.001 and p = 0.025) and post-warm-up (p = 0.001 and p = 0.002) in all conditions. The present study indicates that warm-up consisting of either whole-body vibration, drop jumps, or a combination of both failed to acutely improve CMJ and 3 km volitional pace running performance in physically active males. However, the increase in the CMJ performance was noted after the end of the 3 km run, which may indicate that the warm-up protocols used were insufficient to enhance subsequent performance.

Acute Effects of Percussive Massage Treatment on Drop Jump Performance and Achilles Tendon Stiffness.

This study aimed to investigate the impact of Achilles tendon (AT) mechanical percussion massage (PM) on the passive stiffness of that tendon and subsequent drop jump kinematics. Eleven physically active participants performed two conditions in random order: (i) 60 s of PM applied to each AT (EXP) and (ii) no PM (CTRL). Measurements were performed 5 min before, immediately after, and 5 min following the completion of the PM. In the CTRL, measurements were performed at the same time point but no massage was applied. The two-way ANOVA indicated that there was no statistically significant interaction effect on contact time (p = 0.786), reactive strength index (p = 0.914), and relative peak power (p = 0.896). However, a statistically significant interaction on peak velocity (p = 0.046) and jump height (p = 0.03) was found. Despite that, there was no significant post-hoc comparisons for jump height, it slightly decreased 5 min post-PM (p = 0.136; ES = -0.25; Δ = -3.1%) compared with the CTRL condition (p = 1.00; ES = 0.11; Δ = +1.5%). Friedman's test did not show significant differences in dominant (p = 0.073) and non-dominant limb (p = 0.091) AT stiffness. Although not significant, numerically, the dominant limb AT (p = 0.126; ES = -0.64; Δ = -7.8%) had a larger reduction in stiffness immediately post-PM compared with the non-dominant limb (p = 0.294; ES = -0.26; Δ = -3.6%). The results of this study indicated the temporary effect of PM on the reduction in tissue stiffness. Moreover, these findings show that a mechanical PM might slightly hinder subsequent explosive athletic performance.

Correction: Muscle strength, muscle power and body composition in college-aged young women and men with Generalized Joint Hypermobility.

[This corrects the article DOI: 10.1371/journal.pone.0236266.].

Muscle strength, muscle power and body composition in college-aged young women and men with Generalized Joint Hypermobility.

The aim of this study was an evaluation of the musculoskeletal system in women and men with Generalized Joint Hypermobility (GJH). The study included 87 participants- 40 with Generalized Joint Hypermobility (aged 21.2 ±1.8 years) and 47 (aged 21.0 ±1.3 years) in the control group (CG). The study included the Beighton score, the measurements of body composition, muscle flexibility (Straight Leg Raise test, Popliteal Angle test, Modified Thomas Test), and the measurements of muscle strength and muscle power. T-test and Mann-Whitney U Test were applied to assess the differences between independent groups. The study showed that there were no significant differences (p>.05) in the assessed body composition and the muscle flexibility between both women and men with GJH and the participants in the CG. Under isokinetic conditions for the non-dominant lower extremity, men from the CG received significantly higher (p = .02) flexion peak torque at 180°/s angular velocity. Women from the CG received a statistically significantly lower (p = .04) F/E ratio at 180°/s velocity. Under isometric conditions for both women and men with GJH, there were no statistically significant differences (p>.05) in the maximum torques in knee extension and flexion compared to the CG. For women and men with GJH, the maximum power in the lower extremities and jumping ability were not significantly different (p>.05) compared to the CG participants. The body composition, muscle flexibility, muscle strength, and muscle power of adults with Generalized Joint Hypermobility did not differ compared to healthy participants. The fact that there are no differences does not exclude the efficacy of strength training in increasing levels of muscle strength and its impact on body posture and proprioception or coordination.

Diurnal variation of body height in children with idiopathic scoliosis.

BACKGROUND: Body height (BH) measurement is an important part of the clinical evaluation of children with idiopathic scoliosis (IS) as its progression is defined based on the observation of a growth spurt. OBJECTIVE: The aim of the study is to assess diurnal variation of BH in children with IS. METHODS: BH was measured in 98 children with IS (Cobb angle: 10∘-52∘, mean 21.2∘± 9.9∘) both in standing and sitting position. The measurements were performed 4 times a day - between: (1) 7:00 and 8:00; (2) 11:00 and 12:00; (3) 15:00 and 16:00 and (4) 19:00 and 20:00. RESULTS: A significant decrease in BH during the day was observed in both standing and sitting positions (p< 0.001). The highest decrease in height was observed between the measurements performed between 7:00 and 8:00 and measurements carried out in the evening (19:00-20:00). For standing, the mean loss of height was 0.7 cm (± 0.7), i.e. 0.43% of initial standing height, for sitting the mean decrease in height was 0.7 cm (± 0.7), i.e. 0.79% of initial sitting height. CONCLUSIONS: BH decreases in children with IS during daytime. Due to diurnal BH variation, the time of the day should be recorded when measuring patients with IS.

Low Back Pain and Everyday Functioning of Students.

INTRODUCTION: The aim of the study was to determine the frequency of low back pain episodes (over a period of 12 months) and everyday functioning of students suffering from it. MATERIAL AND METHODS: The study enrolled 1321 students of the 1st, 2nd and 3rd year of Bachelor-level programmes in Physical Education, Physiotherapy, Pedagogics, and Tourism and Recreation at 4 universities in Poland. An original questionnaire was used. A 10-point VAS scale was used to assess pain intensity. The reliability of the questionnaire had been assessed before commencing the study by administering it twice at a month's interval to a group of 20 people. No significant differences were noted between the results obtained in the two tests (p<0.05). RESULTS: Our analysis of the frequency of low back pain episodes showed that the respondents who experienced pain rarely (1-2 episodes per year) constituted the biggest group. With regard to pain intensity, mild pain, reported by 43.4% of the respondents, was most common. Over 20% of the subjects reported severe pain. A considerable percentage of the respondents (over 20%) limited their physical activity because of low back pain and 4.4% had to give up physical activity altogether. Nearly 60% of the subjects reported that the low back pain made it difficult for them to sit for prolonged periods, while nearly 50% had difficulty standing. CONCLUSIONS: 1. This study of a group of students from eastern Poland revealed that low back pain is common. 2. Low back pain interferes with or limits daily activities of the students, such as sitting, standing or physical activity.