Dynamic trunk stabilization: a conceptual back injury prevention program for volleyball athletes

An Intervention to Improve Mental and Physical Health of Undergraduate Nursing Students

BACKGROUND

Nursing students experience poorer mental and physical health relative to students in other health-related disciplines and young adults of similar age outside post-secondary school. Compromised mental and physical health has numerous negative impacts on nursing students and can result in burnout and development of chronic diseases.

PURPOSE

To determine whether an asynchronous online yoga intervention would improve mental and physical health of students.

METHODS

An asynchronous online 6-week yoga intervention was carried out between January and December 2021, using a pre/post design. Participants' symptoms of depression, anxiety, stress, and self-compassion were assessed using the Depression, Anxiety, and Stress Scale and Self-Compassion Scale and core endurance was assessed using the Mackenzie Core Endurance Test prior to commencement and at the conclusion of the program.

RESULTS

Of 114 participants, 68 completed the online program and pre and post measures showed that the mean depression, anxiety, stress, self-compassion and core endurance scores improved significantly (p<0.001) between baseline and study completion.

CONCLUSION

A six-week virtual yoga program significantly improved mental and physical health of undergraduate nursing students. Targeted modifications to the yoga program might enhance participant retention.

Comparison of psoas major activation during standing hip flexion between chronic low back pain and healthy populations

BACKGROUND

The psoas major (PM) has been identified as a potential contributor to chronic low back pain (LBP). However, few studies have investigated the effects of upright functional movement on PM activation in cLBP individuals.

OBJECTIVE

This cross-sectional study aims to compare PM muscle activation characteristics in chronic LBP (cLBP) and healthy subjects during the transition from quiet double-leg standing to standing hip flexion.

METHODS

Ultrasound Imaging was used to assess PM thickness at the lumbar vertebral level of L4-5 in 12 healthy and 12 cLBP participants. The changes in thickness between the test positions were utilized as a proxy for PM activation.

RESULTS

The cLBP group exhibited greater thickness changes on the non-dominant side PM during contralateral hip flexion but not ipsilateral hip flexion (p= 0.369) compared to their healthy counterparts (p= 0.011; cLBP: resting 27.85 mm, activated 34.63 mm; healthy: resting 29.51 mm, activated 29.00 mm). There were no significant differences in dominant side PM thickness changes between the two groups during either contralateral or ipsilateral hip flexion (p= 0.306 and p= 0.077).

CONCLUSION

Our findings suggest a potential overactivation of the PM in the cLBP population. This insight may aid in the development of tailored rehabilitation programs.

Effects of Pilates Exercises on Core Stability After Recovery from COVID-19: A Randomized Controlled Trial

Purpose

The primary objective was to investigate the effects of Pilates exercises on CS, and the secondary objective was to assess static trunk balance after recovery from COVID-19.

Patients and Methods

145 recovered COVID-19 university students between the ages of 19 and 25 participated in this single-blinded, randomized controlled trial study. The participants were divided into a Pilates group and a control group, each of which received a home exercise program. Core muscle endurance was measured using the five basic endurance tests and static balance using the Prokin system with open eyes (OE) and closed eyes (CE) at baseline and after three months of treatment.

Results

All measured parameters showed improvement within the groups after treatment. Group comparison revealed a significant increase in the Pilates group in all core endurance tests (P<0.001). The Prokin system results showed improvement in the Pilates group after treatment, while perimeter with OE, CE, and ellipse area with EC decreased (P<0.001), but there was no significant difference in ellipse with OE between the groups.

Conclusion

Pilates exercises positively improved core muscle endurance and trunk balance in people infected with COVID-19, which will be reflected in their quality of movement patterns and quality of life.

Measuring transversus abdominis activity using pressure biofeedback unit-A technical report

BACKGROUND AND PURPOSE

Pressure biofeedback is a tool that can detect the movement of a structure and may be used as an indicator of muscle function. It's widely used to measure the transversus abdominis (TrA) muscle activity. Pressure biofeedback (PBU) monitors the abdominal wall movement by measuring the pressure change during abdominal hollowing and can indirectly evaluate the TrA muscle function, which is considered as a valuable tool. The evaluation of the training of core muscles, including the transversus abdominis, requires a reliable outcome. Various methods using different positions are used to evaluate the transversus abdominis muscle function. However, it is noted that a standard way of evaluation and training still needs to be improved in research and clinical practice. This technical report discusses the optimal position and technique to measure the TrA muscle activity using PBU, with discussions on the merits and demerits of the body positions.

METHODS

The technical report is presented with a literature review of the PBU measurement of TrA and through observation in the clinical practice. The evaluation methods of TrA, including the position to activate and isolate, are discussed in detail.

RESULTS

Training core muscles does not imply TrA activation, and evaluating isolated TrA and multifidus is essential before intervention. The abdominal drawing-in maneuver effectively activates TrA in various evaluation positions of the body, but when using PBUs, it would be valid in a prone position.

DISCUSSION

Different body positions are practiced to train TrA and core muscles using PBU, commonly adopted by practice are in supine. It's noted that most of the studies lack in establishing the effectiveness of the position in evaluating the TrA muscle activity using PBU. The need for insight into an appropriate technique for evaluating TrA activity is addressed in this technical report. This report presents key points on the complete technique and concludes that the prone position is superior to other positions and recommended for measuring and recording the TrA activity using a PBU.

Spinal Muscle Thickness and Activation during Abdominal Hollowing and Bracing in CrossFit® Athletes

Exercises that improve muscle activation are essential for maintaining spinal stability and preventing low back pain. The purpose of this study was to compare the effects of abdominal hollowing and bracing on the activation of the core muscles in CrossFit® participants using ultrasound and electromyography (EMG). Twenty-four healthy adults aged 21 to 42 years old with at least two years of CrossFit® experience performed three core stability exercises (plank, side plank, bridge) with abdominal hollowing and bracing. We measured the ultrasound relative thickness of the local core muscles (transversus abdominis, internal oblique, and lumbar multifidus), and the EMG percentage of maximal voluntary contraction (MVC) of the global core muscles (rectus abdominis, external oblique, and iliocostalis lumborum). Analysis of variance tests showed that the relative thickness of the local core muscles was greater (p = 0.016) during hollowing (range from 26.8 ± 5.33 to 88.4 ± 11.9% of rest) than bracing (range from 15.9 ± 3.54 to 61.2 ± 15.9% of rest), while the EMG of the global muscles was greater (p = 0.001) in bracing (range from 24.4 ± 7.30 to 72.5 ± 9.17% of MVC) than hollowing (range from 16.4 ± 3.70 to 56.6 ± 7.65% of MVC). These results indicate that the recruitment of spinal muscles during popular exercises is achieved with both hollowing and bracing. Nevertheless, it appears that hollowing tends to recruit more of the local muscles, whilst bracing recruits more of the global muscles. The grading of the exercises varied between muscles and varied between maneuvers, especially for the surface abdominals and lumbar muscles. CrossFit® practitioners can choose to use either hollowing or bracing to activate their core muscles more selectively or more appropriately, depending on the goal and purpose of the exercise.

The effectiveness of injury prevention programs that include core stability exercises in reducing the incidence of knee injury among soccer players: A systematic review and meta-analysis

BACKGROUND: The knee is one of the most common sites of injuries among soccer players. The incidence of knee injuries can be reduced by improving the neuromuscular control and core stability. OBJECTIVE: This study aimed to evaluate the effectiveness of injury prevention programs that include core stability exercises in reducing the incidence of knee injuries among soccer players. METHODS: Data were obtained from different databases (1985–2021). Only randomized controlled trials that used injury prevention programs that include core stability exercise to prevent knee injuries were included. The keywords used during the search were ‘knee injuries’, ‘core stability exercises’, ‘FIFA 11+’, ‘prevention of knee injuries’, ‘anterior cruciate ligament injury’ and variations of these search terms. RESULTS: The pooled results of 7828 soccer players and 863700 exposure h showed an overall injury reduction of 56% per 1000 h of exposure in the intervention group compared to the control group with an injury risk ratio of 0.44 (95% CI 0.321–0.619; P= 0.001). CONCLUSIONS: Injury prevention programs that include core stability exercises reduce knee injury rates among soccer players by 56% (46% in male and 65% in female soccer players).

Strength and Power-Related Measures in Assessing Core Muscle Performance in Sport and Rehabilitation

While force-velocity-power characteristics of resistance exercises, such as bench presses and squats, have been well documented, little attention has been paid to load, force, and power-velocity relationships in exercises engaging core muscles. Given that power produced during lifting tasks or trunk rotations plays an important role in most sport-specific and daily life activities, its measurement should represent an important part of the test battery in both athletes and the general population. The aim of this scoping review was 1) to map the literature related to testing methods assessing core muscle strength and stability in sport and rehabilitation, chiefly studies with particular focus on force-velocity-power characteristics of exercises involving the use of core muscles, 2) and to identify gaps in existing studies and suggest further research in this field. The literature search was conducted on Cochrane Library databases, Scopus, Web of Science, PubMed and MEDLINE, which was completed by SpringerLink, Google Scholar and Elsevier. The inclusion criteria were met in 37 articles. Results revealed that among a variety of studies investigating the core stability and core strength in sport and rehabilitation, only few of them analyzed force-velocity-power characteristics of exercises involving the use of core muscles. Most of them evaluated maximal isometric strength of the core and its endurance. However, there are some studies that assessed muscle power during lifting tasks at different loads performed either with free weights or using the Smith machine. Similarly, power and velocity were assessed during trunk rotations performed with different weights when standing or sitting. Nevertheless, there is still scant research investigating the power-velocity and force-velocity relationship during exercises engaging core muscles in able-bodied and para athletes with different demands on stability and strength of the core. Therefore, more research is needed to address this gap in the literature and aim research at assessing strength and power-related measures within cross-sectional and intervention studies. A better understanding of the power-force-velocity profiles during exercises with high demands on the core musculature has implications for designing sport training and rehabilitation programs for enhancement of athletes' performance and/or decrease their risk of back pain.

Virtual reality balance training versus core stability exercises on balance in patients with unilateral lymphedema

Purpose: The purpose of this study is to compare the effects between Wii fit balance board and core stability exercises on balance dysfunction in patients with unilateral lymphedema. Method: Sixty patients (women) aged 40-60 years with grade 1 or 2 lymphedema were randomly assigned into the following two groups. Group A received the Wii fit balanced exercises for three times per week for four weeks as total treatment duration in form of (Ski Slalom, Advanced Skiing, Ski Jumping followed by Header and Jump Rope).; Group B received core stability exercises for 4 weeks (3times/week) in form of {1- Abdominal bracing (10 repetitions x10 second holds), 2- Curl up (3 sets x 10 repetitions), 3- Supine bridge (3 sets x 10 repetitions), 4- Supine unilateral bridge (3 sets x 10 repetitions for each leg), 5- Plank (3 sets x 10 repetitions) and 6- Bird dog (3 sets x 10 repetitions for each limb)}. Balance was determined using time up and go (TUG) and Wii fit results by using the Wii fit balance board. Balance was measured before and 4 weeks after the treatment program. 

Trunk muscle size and function in volleyball players with and without injuries to the head, neck and upper limb

OBJECTIVE

To investigate trunk muscle size and function in elite and community volleyball players with and without a history of head, neck or upper limb injury.

DESIGN

Cross-sectional observational study.

SETTING

Volleyball training camp or training sessions.

PARTICIPANTS

86 volleyball players (elite = 29; community = 57).

MAIN OUTCOME MEASURES

Information regarding history of head, neck or upper limb injuries was collected by self-report questionnaires. Trunk muscle size (multifidus, transversus abdominis, internal oblique and quadratus lumborum) and voluntary contraction (multifidus, transversus abdominis, internal oblique) were assessed using ultrasound imaging.

RESULTS

For trunk muscle size, no significant differences were found between elite and community volleyball players with and without a history of injury (all p > 0.05). A significant difference was found for voluntary contraction of the multifidus and transversus abdominis muscles for elite and community volleyball players with and without a history of injury (all p < 0.05).

CONCLUSION

A difference in trunk muscle contraction but no change in trunk muscle size in players with a history of head, neck or upper limb injuries may represent an altered muscle recruitment pattern rather than a deficiency in trunk muscle strength. Prospective studies are required to determine if these adaptations are compensatory (and protective) or predispose players to further injuries.

Hip and Core Muscle Activation During High-Load Core Stabilization Exercises

BACKGROUND

There is some evidence that high-load lumbar stabilization exercises, such as back bridge, can recruit both local and global muscles.

HYPOTHESIS

Therapeutic exercises would optimize gluteus maximus (GMax), gluteus medius (GMed), multifidus (MF), and transversus abdominis (TrA) activation, while minimizing the activation of the tensor fascia latae (TFL) and erector spinae (ES) muscles in healthy individuals.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

LEVEL OF EVIDENCE

Level 4.

METHODS

In this cross-sectional study, surface electromyography (EMG) of GMax, GMed, TFL, TrA, MF, and ES was used to quantify the gluteal-to-TFL muscle activation (GTA) index and a ratio of local to global (L/G) lumbar muscles during (1) the elbow-toe exercise in the prone position, (2) the elbow-toe with right left lifted, (3) the hand-knee with left arm and right leg lifted, (4) the back bridge, (5) the back bridge with right leg lifted, (6) the back bridge with left leg lifted, (7) the side bridge with left leg lifted, (8) the side bridge with right leg lifted, and (9) the elbow-toe with right leg horizontally lifted exercises in healthy individuals (20 men, 20 women; age, 25 ± 4 years).

RESULTS

The back bridge exercise with left leg lift generated the highest L/G muscles activity ratio (L/G = 3.35) while the hand-knee exercise yielded the lowest L/G muscles activity ratio (L/G = 1.21). The side bridge exercise with left elbow and foot and lifting the right leg (GTA = 63.78), hand-knee exercise (GTA = 49.62), back bridge (GTA = 28.05), and elbow-toe exercise with left leg horizontally lifted (GTA = 23.02) generated the highest GTA indices, respectively. Meanwhile, the normalized EMG amplitude for GMax was significantly less than the TFL, for elbow-toe exercise (P < 0.001), back bridge with left leg lift (P = 0.001), side bridge exercise with the right elbow and foot and lifting the left leg (P = 0.002), and elbow-toe exercise with right leg horizontally lifted (P < 0.001).

CONCLUSION

The highest GTA indexes were observed during (1) the side bridge lifting the dominant leg and (2) the hand-knee horizontally lifting dominant leg, respectively. The L/G ratio was highest during (1) the back bridge lifting nondominant leg, (2) back bridge, and (3) back bridge lifting dominant leg, respectively. This study supports the use of back bridge exercises to strengthen the MF and side bridges to improve gluteal muscle activation.

CLINICAL RELEVANCE

The highest GTA index was observed in the side bridge lifting the right leg. Highest L/G ratio was in the back bridge with nondominant leg lifted. This study supports the use of back bridge exercises to strengthen the MF. This study supports the use of side bridges to improve gluteal muscle activation.

Injury Epidemiology and Time Lost From Participation in Women's NCAA Division I Indoor Versus Beach Volleyball Players

Background:

Beach volleyball officially became a National Collegiate Athletic Association (NCAA) Division I sport in 2015-2016. Few studies have examined the epidemiology of injuries in indoor versus beach volleyball in NCAA Division I athletes.

Purpose:

To compare the epidemiology of injuries and time lost from participation between female NCAA Division I athletes who participate in indoor versus beach volleyball.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Injury surveillance data (2003-2020) were obtained using an institutional database for all NCAA Division I women’s beach or indoor volleyball athletes. The total injury rate was expressed per 1000 hours played. The injury rate per body site was calculated by dividing the number of injuries in each body region by the total number of injuries. The frequency of injury per body site was also expressed as number of injuries per 1000 hours of practice or number of injuries per 1000 hours of game. The injury rate (total and per body site) and time lost from participation were compared between indoor and beach volleyball athletes.

Results:

Participants were 161 female NCAA Division I volleyball athletes (53 beach volleyball and 108 indoor volleyball athletes). In total, 974 injuries were recorded: 170 in beach volleyball and 804 in indoor volleyball. The injury rates for beach versus indoor volleyball were 1.8 versus 5.3 injuries per 1000 hours played (P < .0001). Indoor volleyball athletes had significantly higher injury rates compared with beach volleyball players for concussion (7.5% vs 6.5%; P < .0001) and knee injury (16.7% vs 7.6%; P = .0004); however, the rate of abdominal muscle injury was significantly higher in beach versus indoor volleyball (11.8% vs 4.7%; P = .0008). Time lost from sport participation was significantly longer in beach versus indoor volleyball for knee (24 vs 11 days; P = .047), low back (25 vs 17 days; P = .0009), and shoulder (52 vs 28 days; P = .001) injuries.

Conclusion:

Based on this study, injury was more likely to occur in indoor compared with beach volleyball. Sport-related concussion and knee injuries were more common in indoor volleyball, but the rate of abdominal muscle injury was higher in beach volleyball. Beach volleyball players needed longer time to recover after injuries to the knee, low back, and shoulder.

Association between trunk core muscle thickness and functional ability in subacute hemiplegic stroke patients: an exploratory cross-sectional study

BACK GROUND

Balance impairment could occur due to weakness of the core muscles in stroke patients.

OBJECTIVE

To investigate the association between functional ability, including trunk balance and core muscle thickness using ultrasonography in subacute hemiplegic stroke patients.

METHODS

The muscle thickness of the anterior and posterior trunk muscles was measured using ultrasonography. For the evaluation of trunk balance, trunk impairment scale and Berg balance scale (BBS) were used. The functional ambulatory scale (FAS), timed up-and-go test, 10 m gait velocity, functional reach (FR), and functional independence measure were also assessed for functional ability.

RESULTS

Overall, 41 patients with subacute hemiplegic stroke were included. Partial correlation analysis showed that posterior trunk muscle thickness was significantly correlated with BBS, FAS, and FR. As for the paralytic side, the posterior trunk muscle thickness of both paretic and nonparetic sides presented a significant relationship with BBS, FAS, and FR. The quadratus lumborum (QL) thickness of both sides showed a significant relationship with BBS, FAS, and FR.

CONCLUSIONS

The thickness of the posterior trunk muscles, especially the QL, on both the paretic and nonparetic sides, was significantly related with the functional ability after stroke. The exercise program of core posterior trunk muscles closely related with functional ability would be helpful to improve trunk balance and ambulatory function in subacute stroke patients.

Association between lower back pain and lower extremity pain among young volleyball players: A cross-sectional study

BACKGROUND

Lower back pain (LBP), as well as lower extremity injuries, are major problems among young volleyball players. Nevertheless, only few studies have focused on the relationship between lower extremity injuries and LBP.

OBJECTIVE

This study investigated the association between LBP and lower extremity pain, including knee and ankle pain, among young volleyball players.

DESIGN

Cross-sectional study.

SETTING

Amateur sports association.

PARTICIPANTS

Elementary and middle school-aged athletes (6-15 years of age).

MAIN OUTCOME MEASURES

LBP and lower extremity pain.

RESULTS

A total of 566 young volleyball players participated in this study. The point prevalence of LBP among young volleyball players was 9.5%. Using absence of lower extremity pain as a reference, the adjusted odds ratio (95% confidence interval) for LBP was 11.07 (5.64-21.71) in the presence of lower extremity pain.

CONCLUSIONS

LBP is associated with Lower extremity pain among young volleyball players. Careful attention should be paid to lower extremity complaints to prevent and treat LBP among young volleyball players.

The effects of a standardized belly dance program on perceived pain, disability, and function in women with chronic low back pain

BACKGROUND

An alternative approach to facilitate movement and control through the trunk and pelvis is belly dancing. Investigations of belly dancing mechanics indicate similar muscular activation patterns of those known to influence chronic low back pain (cLBP). However, no documented studies have examined its effectiveness as a treatment for cLBP.

OBJECTIVE

The purpose of this study was to investigate the influence of a standardized belly dance program in women with cLBP.

METHODS

A single subject design was used to evaluate weekly outcomes during a three-week baseline period, six-week belly dance program, and again at a two-month follow-up. Outcome measures for pain, disability, function, and fear-avoidance beliefs were utilized.

RESULTS

Two subjects completed the program. No significant differences were noted during the baseline assessment period. At two months, subject one demonstrated change scores of -1.12, -1%, and 2.2 for pain, disability, and function respectively while subject two demonstrated change scores of 5.4, 5%, and 1.1 for pain, disability, and function, respectively. Subject one showed a clinically significant change score for both fear avoidance of work and physical activity, with score changes of 4 and 3.3, respectively.

CONCLUSION

The results of this study suggest a standardized belly dance program may positively influence pain and function in women with cLBP.

Injury risk is low among world-class volleyball players: 4-year data from the FIVB Injury Surveillance System

Background

Little is known about the rate and pattern of injuries in international volleyball competition.

Objective

To describe the risk and pattern of injuries among world-class players based on data from the The International Volleyball Federation (FIVB) Injury Surveillance System (ISS) (junior and senior, male and female).

Methods

The FIVB ISS is based on prospective registration of injuries by team medical staff during all major FIVB tournaments (World Championships, World Cup, World Grand Prix, World League, Olympic Games). This paper is based on 4-year data (September 2010 to November 2014) obtained through the FIVB ISS during 32 major FIVB events (23 senior and 9 junior).

Results

The incidence of time-loss injuries during match play was 3.8/1000 player hours (95% CI 3.0 to 4.5); this was greater for senior players than for junior players (relative risk: 2.04, 1.29 to 3.21), while there was no difference between males and females (1.04, 0.70 to 1.55). Across all age and sex groups, the ankle was the most commonly injured body part (25.9%), followed by the knee (15.2%), fingers/thumb (10.7%) and lower back (8.9%). Injury incidence was greater for centre players and lower for liberos than for other player functions; injury patterns also differed between player functions.

Conclusions

Volleyball is a very safe sport, even at the highest levels of play. Preventive measures should focus on acute ankle and finger sprains, and overuse injuries in the knee, lower back and shoulder.

The effect of trunk coordination exercise on dynamic postural control using a Core Noodle

OBJECTIVE

To investigate the influence of trunk coordination exercise on dynamic postural control relative to postural sway.

METHOD

The effects of trunk coordination exercises were examined using a Core Noodle for the postural sway in healthy students who were assigned to an exercise or control group. The independent variable was the extent of exposure to Core Noodle exercise, and the dependent variable was dynamic postural control. A stabilometer, which measures dynamic postural control, was used to evaluate the effectiveness of the exercises. In addition, center of gravity movements were assessed using a Gravicorder G-620 stabilometer in which the subject was asked to shift their center of gravity between 2 circles on a computer monitor. Pre- and post-intervention dynamic postural control was statistically evaluated between the exercise group and control group using the Mann-Whitney test. Finally, we investigated the application of these exercises for a stroke patient.

RESULTS AND CONCLUSION

For post-intervention, the envelop area, mean length of the pathways between 2 circles, and the number of circles were significantly higher in the exercise group. Trunk coordination exercise performed Core Noodle may be used to enhance the dynamic postural balance of healthy young adults, and it can also be adapted for stroke patients.

Core stability training for injury prevention

CONTEXT

Enhancing core stability through exercise is common to musculoskeletal injury prevention programs. Definitive evidence demonstrating an association between core instability and injury is lacking; however, multifaceted prevention programs including core stabilization exercises appear to be effective at reducing lower extremity injury rates.

EVIDENCE ACQUISITION

PUBMED WAS SEARCHED FOR EPIDEMIOLOGIC, BIOMECHANIC, AND CLINICAL STUDIES OF CORE STABILITY FOR INJURY PREVENTION (KEYWORDS: "core OR trunk" AND "training OR prevention OR exercise OR rehabilitation" AND "risk OR prevalence") published between January 1980 and October 2012. Articles with relevance to core stability risk factors, assessment, and training were reviewed. Relevant sources from articles were also retrieved and reviewed.

RESULTS

Stabilizer, mobilizer, and load transfer core muscles assist in understanding injury risk, assessing core muscle function, and developing injury prevention programs. Moderate evidence of alterations in core muscle recruitment and injury risk exists. Assessment tools to identify deficits in volitional muscle contraction, isometric muscle endurance, stabilization, and movement patterns are available. Exercise programs to improve core stability should focus on muscle activation, neuromuscular control, static stabilization, and dynamic stability.

CONCLUSION

Core stabilization relies on instantaneous integration among passive, active, and neural control subsystems. Core muscles are often categorized functionally on the basis of stabilizing or mobilizing roles. Neuromuscular control is critical in coordinating this complex system for dynamic stabilization. Comprehensive assessment and training require a multifaceted approach to address core muscle strength, endurance, and recruitment requirements for functional demands associated with daily activities, exercise, and sport.

Effect of movement speed on trunk and hip exercise performance

The influence of speed on trunk exercise technique is poorly understood. The aim of this study was to analyse the effect of movement speed on the kinematics and kinetics of curl-up, sit-up and leg raising/lowering exercises. Seventeen healthy, recreationally trained individuals (13 females and 4 males) volunteered to participate in this study. Four different exercise cadences were analysed: 1 repetition/4 s, 1 repetition/2 s, 1 repetition/1.5 s and 1 repetition/1 s. The exercises were executed on a force plate and recorded by three cameras to conduct a 3D photogrammetric analysis. The cephalo-caudal displacement of the centre of pressure and range of motion (ROM) of six joints describing the trunk and hip movements were measured. As sit-up and curl-up speed increased, hip and knee ROM increased. Dorsal-lumbar and upper trunk ROM increased with speed in the curl-up. Faster cadence in the sit-up exercise had minimal effect on trunk ROM: only the upper trunk ROM decreased significantly. In the leg raising/lowering exercise there was a decrease in the pelvic tilt and hip ROM, and increased knee flexion ROM. During higher speed exercises, participants modified their technique to maintain the cadence. Thus, professionals would do well to monitor and control participants' technique during high-speed exercises to maintain performance specificity. Results also suggest division of speed into two cadence categories, to be used as a reference for prescribing exercise speed based on preferred outcome goals.

Overuse in volleyball training/practice: A review on shoulder and spine-related injuries

Overuse injuries are predominant in sports involving the repetition of similar movements patterns, such as in volleyball or beach volleyball, and they may represent as much a problem as do acute injuries. This review discusses the prevalence of two of the most common overuse-related injuries in volleyball: shoulder and back/spine injuries. Risk factors and the aetiology of these injuries are illustrated in order to make possible to initiate preventive programme or post-injuries solutions. Data collected from literature showed a moderately higher injury rate for overuse shoulder injuries compared to the back/spine (19.0 ± 11.2% and 16.8 ± 9.7%, respectively). These data could be underestimated, and future epidemiological studies should consider overuse injuries separately from the others, with new methodological approaches. In addition to age, biomechanical and anatomical features of a volleyball technique utilised in game and the amount of hours played are considered as the main risk factors for overuse upper limb injuries, both for professional and recreational athletes. Together with post-injuries solutions, great importance has to be placed on preventive programmes, such as preventive rehabilitation, stretching, adequate warm up, strength-power exercises, etc. Furthermore, it is particularly suggested that coaches and players work together in order to develop new game/training techniques that minimise stresses and range of motion of the principal anatomical structures involved, while maintaining athletes performance.

Stabilizing function of the diaphragm: dynamic MRI and synchronized spirometric assessment

The aim was to describe diaphragmatic behavior during postural limb activities and examine the ventilatory and stabilizing functions of the diaphragm. Thirty healthy subjects were examined in the supine position using a dynamic MRI system assessed simultaneously with specialized spirometric readings. The diaphragmatic excursions (DEs) were measured at three diaphragmatic points in the sagittal plane; the diaphragm positions (DPs) as related to a reference horizontal baseline were determined. Measurements were taken during tidal breathing (TB) and isometric flexion of upper or lower extremities against external resistance together with TB. Mean DE in both upper and lower postural limb activities was greater compared with the TB condition (P < 0.05), with the effect greater for lower limb activities. Inspiratory DPs in the upper and lower extremity activities were lower compared with TB alone (P < 0.01). Expiratory DP was lower only for lower extremity activities (P < 0.01). DP was most affected at the apex of the crescent and crural (posterior) portion of the diaphragm. DEs correlated strongly with tidal volume (Vt) in all conditions. Changes in DEs relative to the initial value were minimal for upper and lower extremities but were related to lower values of Vt (P < 0.03). Significant involvement of the diaphragm in the limb postural activities was found. Resulting DEs and DPs differed from the TB conditions, especially in lower extremity activities. The differences between the percent changes of DEs vs. Vt found for lower extremity activities were confirmed by both ventilatory and postural diaphragm recruitment in response to postural demands.