A cross-sectional analysis of the muscle strength, spinal shrinkage, and recovery during a working day of military police officers.

OBJECTIVE: Military personnel has a large prevalence of back pain, especially those involved in patrolling routines, as they wear heavy protective equipment. Patrolling includes long periods of sustaining the protective equipment in a sitting or in a motor vehicle (motorcycle or car). Thus, understanding spinal loading of military police officers after patrolling by car (CAR; n = 14), motorcycle (MOT; n = 14), and administrative (ADM; n = 14) routines is relevant to establish preventive strategies. METHODS: The torque of the trunk and working and anthropometric characteristics were assessed to explain spinal loading using stature variation measures. Precise stature measures were performed before and after a 6 h journey (LOSS) and 20 min after a resting posture (RECOV). The trunk extensor (PTE BM-1 ) and flexor (PTF BM-1 ) muscles' isometric peak torque were measured before the working journey. RESULTS: The LOSS was similar between CAR and MOT (4.8 and 5.8 mm, respectively) after 6 h of patrolling. The ADM presented the lowest LOSS (2.8 mm; P < .05). No changes in RECOV between groups were observed (P > .05). Vibration may explain the greater spinal loading involved in patrolling in comparison to the ADM. A GLM analysis revealed that BMI was the only explanatory factor for stature loss. No independent variables explained RECOV. The ability of the trunk muscles to produce force did not influence LOSS or RECOV. CONCLUSIONS: Military police officers involved in patrolling may require greater post-work periods and strategies designed to reduce the weight of the protective apparatus to dissipate spinal loading. The external load used in patrolling is a relevant spinal loading factor.

Defensive High-Anxious Individuals Demonstrate Difference Responses to Pain Management to Those with Lower Levels of Defensiveness and Anxiety.

OBJECTIVES: Few studies have considered the effect of Weinberger et al.'s personality types on the management of pain. The aims of this study were to (1) identify whether the relationships between pain intensity, cognitive factors, and disability at 3 and 6 months postbaseline differ as a result of personality type; and (2) identify whether personality type affects the likelihood of achieving a minimal clinically important change in pain intensity or disability at 3 and 6 months. METHOD: Patients completed a set of validated questionnaires assessing personality type, cognitive factors, pain intensity, and disability at 3 and 6 months postbaseline. RESULTS: A greater proportion of defensive high-anxious individuals reported improvement for both pain (3 months = 25%; 6 months = 38%) and disability (3 months = 35%; 6 months = 50%) and showed stronger links between improvements in pain and disability and baseline psychological factors than nonextreme individuals. CONCLUSIONS: The high proportion of defensive high-anxious individuals highlights the need for psychologically based interventions to be delivered earlier in the care process. Stratifying the population, based on personality type, may allow for more targeted interventions, which could be more cost effective and reduce the number of patients remaining in the care system.

Eye Gaze Markers Indicate Visual Attention to Threatening Images in Individuals with Chronic Back Pain.

Research into attentional biases and threatening, pain-related information has primarily been investigated using reaction time as the dependent variable. This study aimed to extend previous research to provide a more in depth investigation of chronic back pain and individuals' attention to emotional stimuli by recording eye movement behavior. Individuals with chronic back pain (n = 18) were recruited from a back rehabilitation program and age and sex matched against 17 non-symptomatic controls. Participants' eye movements were recorded whilst they completed a dot probe task, which included back pain specific threatening images and neutral images. There were no significant differences between chronic pain and control participants in attentional biases recorded using reaction time from the dot probe task. Chronic pain participants, however, demonstrated a significantly higher percentage of fixations, larger pupil diameter, a longer average fixation duration and faster first fixation to threatening compared to neutral images. They also had a significantly longer average fixation duration and larger pupil diameter to threatening images compared to control participants. The findings of this study suggest eye gaze metrics may provide a more sensitive measure of attentional biases in chronic pain populations. These findings may have important therapeutic implications for the patient and therapist.

A qualitative investigation of factors that matter to individuals in the pain management process.

OBJECTIVE: Chronic musculoskeletal pain is a complex condition to manage with widespread consequences including physical disability, psychosocial effects and increased use of healthcare. Previous research has found patients' experiences within health care can be influenced by factors such as expectations, therapist characteristics and treatment process. This study used patient interviews to identify the key factors that influence individuals' experiences in the management of chronic pain. DESIGN: Qualitative study using semi-structured interviews in either a home or hospital setting. METHODS: Semi-structured interviews were conducted on eight participants attending hospital-based pain management. Participants were asked about their experiences of pain management and living with a chronic pain condition. Interviews were transcribed and analysed thematically. RESULTS: Three main themes were identified; impact of their condition on daily life, clinical interactions and the pain management process. Understanding the condition was a key factor for the patients, in particular, explanation by the clinician. The temporality of their pain meant timing of appointments was critical. Patients reported factors such as family days and follow-up sessions would improve their treatment experience. CONCLUSIONS: This study highlighted important factors for healthcare professionals and patients in the management of chronic pain. Participants indicated a desire to understand their condition and learn strategies for self-management to allow them to cope better. As patients found benefit from being involved in the management process, discussions around the options for treatment may enhance management and rehabilitation. It is important we continue to research factors important to individuals with musculoskeletal pain to find an effective, evidence-based framework for understanding and managing this condition. Implications for rehabilitation This study highlights the importance to patients of being given information to help them understand their pain condition and to learn strategies for self-management to cope better. Where information was not provided and inadequate time allowed for questioning and discussion, patients tended to desire more frequent access to the care services. More effective communication may result in reduced demand and more efficient management. Patients suggested that ongoing peer support may offer an alternative to clinician-led services.

Personality Type Influences Attentional Bias in Individuals with Chronic Back Pain.

Attentional biases reflect an individual's selective attention to salient stimuli within their environment, for example an experience of back pain. Eysenck suggests that different personality types show different attentional biases to threatening information. This study is the first to test Eysenck's theory within a chronic back pain population by investigating the attentional biases of four different personality types using a back pain specific dot-probe paradigm. Participants were 70 volunteers (45 female) recruited from a back rehabilitation program at an NHS Trust. The four groups were selected on their trait anxiety and defensiveness scores: defensive high-anxious; high-anxious; repressor and non-extreme. Participants completed a dot probe task comprising 20 practice trials and 250 experimental trials. The experimental trials contained 100 threat-neutral pairs, 100 positive-neutral pairs and 50 neutral-neutral image pairings. The threat images were taken from the Photograph Series of Daily Activities (PHODA) and the neutral and positive images from the International Affective Picture System (IAPS) image bank. The results provided partial support for Eysenck's theory; defensive high-anxious individuals showed an attentional bias for threatening information compared to high-anxious individuals who demonstrated no bias. Repressors showed an avoidant bias to threatening images and an attentional bias to positive stimuli relative to neutral images. The clear difference in responses demonstrated by high-anxious individuals who vary in defensiveness highlight the need for separate investigation of these heterogeneous groups and help to explain the cognitive processes of defensive high-anxious individuals within a pain population. The demonstration of an attentional bias in this group to threatening information could explain why defensive high-anxious individuals are more likely to re-present for treatment.

Misuse of "Power" and Other Mechanical Terms in Sport and Exercise Science Research.

Despite the Système International d'Unitès (SI) that was published in 1960, there continues to be widespread misuse of the terms and nomenclature of mechanics in descriptions of exercise performance. Misuse applies principally to failure to distinguish between mass and weight, velocity and speed, and especially the terms "work" and "power." These terms are incorrectly applied across the spectrum from high-intensity short-duration to long-duration endurance exercise. This review identifies these misapplications and proposes solutions. Solutions include adoption of the term "intensity" in descriptions and categorizations of challenge imposed on an individual as they perform exercise, followed by correct use of SI terms and units appropriate to the specific kind of exercise performed. Such adoption must occur by authors and reviewers of sport and exercise research reports to satisfy the principles and practices of science and for the field to advance.

Influence of Defensiveness on Disability in a Chronic Musculoskeletal Pain Population.

OBJECTIVE: This study aimed to identify the following: (1) the proportion of the defensive high-anxious personality type in a chronic pain population; (2) whether personality type affects the relationships between cognitive factors and disability. METHOD: Sixty patients with chronic musculoskeletal pain, referred to a hospital for treatment, completed questionnaires assessing defensiveness, trait anxiety, pain intensity, disability, depression, catastrophizing, self-efficacy, and kinesiophobia. Personality type was assessed using the State-Trait Anxiety Inventory and the Marlowe-Crowne Social Desirability Scale. RESULTS: Within the defensive high-anxious group, lower levels of self-efficacy, and high levels of depression and catastrophizing most strongly predicted perceptions of disability. Interestingly, the cognitive variables failed to significantly predict disability for individuals lower in anxiety and defensiveness; however, pain intensity did have a greater effect, explaining 36% of the variance. CONCLUSIONS: The interaction between defensiveness and anxiety plays an important role in patients' perceptions of, and outcomes from, chronic pain. Differentiating the defensive high-anxious group revealed different patterns of relationship between a range of cognitive factors and disability. This highlights the necessity of assessing personality characteristics that include defensiveness in order to identify those individuals who may be more vulnerable to cognitive factors influencing their perceptions of disability. If personality type is identified as a predictor of poor adjustment, interventions could be customized to the unique needs of this group (eg. high defensive and anxious individuals).

Vertical jump fatigue does not affect intersegmental coordination and segmental contribution / Fadiga em salto vertical não afeta a coordenação intersegmental e contribuição segmental / Fatiga salto vertical no afecta a la coordinación entre segmentos y la contribución segmentaria

The aim of this study was to describe the intersegmental coordination and segmental contribution during intermittent vertical jumps performed until fatigue. Seven male visited the laboratory on two occasions: 1) the maximum vertical jump height was determined followed by vertical jumps habituation; 2) participants performed intermittent countermovement jumps until fatigue. Kinematic and kinetic variables were recorded. The overall reduction in vertical jump height was 5,5%, while the movement duration increased 10% during the test. The thigh segment angle at movement reversal significantly increased as the exercise progressed. Non-significant effect of fatigue on movement synergy was found for the intersegmental coordination pattern. More than 90% of the intersegmental coordination was explained by one coordination pattern. Thigh rotation contributed the most to the intersegmental coordination pattern, with the trunk second and the shank the least. Therefore, one intersegmental coordination pattern is followed throughout the vertical jumps until fatigue and thigh rotation contributes the most to jump height...

"Fadiga em salto vertical não afeta a coordenação intersegmental e contribuição segmental." O objetivo deste estudo foi descrever a coordenação entre segmentos e suas contribuições durante saltos verticais intervalados realizados até a fadiga. Sete indivíduos visitaram o laboratório em duas ocasiões: 1) foi determinada a altura máxima do salto vertical e realizada familiarização com saltos verticais; 2) participantes realizaram saltos verticais em contramovimento até a fadiga. Foram coletadas variáveis cinemáticas e cinéticas. A altura do salto vertical reduziu 5,5% e duração do movimento aumentou 10%. O ângulo da coxa no instante de reversão do movimento aumentou durante o exercício. A fadiga na sinergia do movimento não influenciou na coordenação intersegmental. Acima de 90% da coordenação entre segmentos foi explicada por um padrão coordenativo. A rotação da coxa foi o que mais contribuiu com o padrão coordenativo, seguido pelo tronco e perna. Portanto, em saltos verticais realizados até a fadiga, a coordenação intersegmental é mantida e a rotação da coxa tem maior contribuição na altura do salto...

"Fatiga salto vertical no afecta a la coordinación entre segmentos y la contribución segmentaria." El objetivo fue describir la coordinación entre los segmentos y sus contribuciones durante los saltos verticales realizadas hasta la fatiga. Siete sujetos visitaron laboratorio dos ocasiones: 1) determinó la máxima altura en el salto vertical y amistad con los saltos verticales; 2) participantes completaron saltos verticales contramovimento la fatiga. Se recogieron las variables cinemáticas y cinéticas. La altura del salto vertical disminuyó 5,5% y la duración del movimiento se incrementó 10%. El ángulo del muslo en instante de inversión del movimiento aumentó durante ejercicio. No hubo efecto de fatiga en sinergia de movimiento para la coordinación de movimientos. Más del 90% de coordinación entre sectores ha sido explicado por un patrón coordinativo. La rotación del muslo fue mayor contribuyente la coordinación de movimientos, seguido por tronco y piernas. En los saltos verticales realizados hasta la fatiga se mantiene coordinación entre segmentos y rotación del muslo tiene mayor contribución en altura del tacón...

Short-term effect of superficial heat treatment on paraspinal muscle activity, stature recovery, and psychological factors in patients with chronic low back pain.

OBJECTIVE: To test the hypothesis that patients with chronic low back pain (CLBP) would have reduced paraspinal muscle activity when wearing a heat wrap and that this would be associated with increased stature recovery and short-term improvements in psychological factors. DESIGN: A within-subject repeated-measures design. Muscle activity and stature recovery were assessed before and after a 40-minute unloading period, both without a heat wrap and after 2 hours of wear. Questionnaires were completed after both sessions. SETTING: Hospital physiotherapy department. PARTICIPANTS: Patients with CLBP (n=24; age, 48.0±9.0 y; height, 166.6±7.3 cm; body mass, 80.2±12.9 kg) and asymptomatic participants (n=11; age, 47.9±15.4 y; height, 168.7±11.6 cm; body mass, 69.3±13.1 kg) took part in the investigation. Patients on the waiting list for 2 physiotherapist-led rehabilitation programs, and those who had attended the programs during the previous 2 years, were invited to participate. INTERVENTION: Superficial heat wrap. MAIN OUTCOME MEASURES: Paraspinal muscle activity, stature recovery over a 40-minute unloading period, pain, disability, and psychological factors. RESULTS: For the CLBP patients only, the heat wrap was associated with a reduction in nonnormalized muscle activity and a positive short-term effect on self-report of disability, pain-related anxiety, catastrophizing, and self-efficacy. Changes in muscle activity were correlated with changes in stature recovery, and both were also correlated to changes in psychological factors. CONCLUSIONS: Use of the heat wrap was associated with a decrease in muscle activity and a short-term improvement in certain aspects of well-being for the CLBP patients. The results confirm the link between the biomechanical and psychological outcome measures.

Diurnal variation in stature: do those with chronic low-back pain differ from asymptomatic controls?

BACKGROUND: Stature loss is a commonly used measure of spinal load. The aim of this study was to investigate the pattern of diurnal stature change in those with and without chronic low-back pain, over a 24-h period. METHODS: Eight participants with chronic low-back pain (age 24.6 (SD 4.3) years, height 1.76 (SD 0.08) m, body mass 72.8 (SD 11.1) kg) and eight controls (age 21.8 (SD 2.0) years, height 1.75 (SD 0.10) m, body mass 71.8 (SD 11.6) kg) participated in this investigation. Twenty-four stature measurements were performed over a 24-h period. FINDINGS: The trough to peak variation in stature of 17.9 mm (low-back pain group) and 17.6mm (control group) did not differ between groups (P>0.05). Both groups experienced greatest stature change in the 1st hour after rising (31.3% [low-back pain] and 44.6% [control] of total stature change). At approximately 18:00h the LBP group reached a plateau whilst the control group continued to lose stature. Between 14:00 and 18:00h both groups demonstrated a previously unreported recovery of stature. A significant correlation was found between low-back discomfort and stature change in the low-back pain group only. INTERPRETATION: No significant difference existed between groups in relation to total stature loss; however the low-back pain group appeared to reach their nadir earlier, possibly exposing other spinal structures to loading for a greater duration. This is supported by the relationship found between stature loss and discomfort. The reversal in stature loss in the afternoon may be of clinical significance and warrants further investigation.

Effects of 4-weeks of asynchronous hand-rim wheelchair practice on mechanical efficiency and timing.

PURPOSE: To investigate the consequence on gross mechanical efficiency (GE), arm frequency and sub-maximal performance, of paced and unpaced practice during asynchronous hand-rim wheelchair propulsion. METHODS: Twenty-five able-bodied participants performed five, 4-min exercise bouts at 1.7 m/s, at the freely chosen frequency (FCF) and four paced arm frequencies of 60, 80, 120 and 140% FCF. GE, arm frequency and measures of sub-maximal performance were determined. Participants were assigned to an unpaced (FCF, N = 9), paced (80% FCF, N = 8) or control (CON, N = 8) no practice group. The FCF and 80% FCF groups received 4-weeks (unpaced and paced, respectively) propulsion practice (three sessions·per wk, four 4 min/trials; 33-35 W) at 1.7 m/s on a wheelchair ergometer. Following practice, the pre-testing protocol was repeated. RESULTS: Mean GE showed a relative increase in both experimental groups (21 and 17%; FCF and 80% FCF respectively; p = 0.001) compared to no change in CON (-1.5%). The FCF arm frequency decreased in both experimental groups (p = 0.001), with larger changes evident following FCF practice. CONCLUSION: Four weeks of unpaced or paced practice had a beneficial effect on GE. This improvement seems to be associated with a reduction in arm frequency.

Changes in intervertebral disk dimensions after a loading task and the relationship with stature change measurements.

UNLABELLED: Lewis SE, Fowler NE. Changes in intervertebral disk dimensions after a loading task and the relationship with stature change measurements. OBJECTIVE: To test the hypothesis that there would be a linear relationship between overall stature change determined by stadiometry and markers of lumbar disk height loss determined from magnetic resonance imaging (MRI). DESIGN: The short-term loading response of the lumbar spine was evaluated with both stadiometry and MRI, using a within-subject repeated-measures design. Measures were obtained both before and after 15 minutes of walking wearing a weighted vest (20% of body mass). Stature loss measured on the stadiometer was compared with change in lumbar spine length assessed from the MRI images. SETTING: A university laboratory. PARTICIPANTS: Participants (N=13; mean age +/- SD, 28.5+/-5.2y; mean height +/- SD, 1.76+/-0.10m; mean body mass +/- SD, 76.6+/-14.9kg) were invited to take part in the investigation. The group was mixed (9 men, 4 women) and comprised people with no history of low back pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Lumbar spine length assessed via MRI and stature change measured via stadiometry. RESULTS: A significant height loss was observed over the complete lumbar spine (P<.05), and a significant correlation was found between the decrease in posterior spine length and stature loss (r=.61). CONCLUSIONS: The results were supportive of the use of stadiometry as an indirect measure of changes in intervertebral disk height.

Stretching exercise program improves gait in the elderly.

BACKGROUND: Ageing is characterized by a number of physical changes that contribute to a decline in the ability to perform daily tasks. Stretching has been proposed to reduce hip flexion contracture and increase hip and pelvis range of motion, thus improving gait performance. OBJECTIVE: The purpose of this study was to determine whether a supervised stretching program designed to improve the range of motion of the lower limbs alters gait kinematics in older adults. METHODS: Twenty healthy older adult women (65.9 +/- 4.2 years old and BMI 24.9 +/- 3.5) were divided into 2 groups. The experimental group undertook 12 sessions of stretching exercises, whereas the control group did not engage in any physical activity. Gait performance was assessed at the beginning of the experiment and after the 4-week intervention period. RESULTS: Those in the experimental group showed increased step length, higher velocity and reduced double support time after training. In addition, participants involved in the stretching program showed greater anterior and lateral pelvis tilt and also greater rotation (p < 0.05). CONCLUSIONS: Based on our results, we can suggest that a supervised stretching program is effective to alter a number of gait variables. Moreover, after the stretching protocol, aged participants displayed gait parameters which were similar to those reported in young healthy adults. Therefore, stretching can be used as an effective means to improve range of motion and reverse some age-related changes that influence gait performance.

Stature recovery after sitting on land and in water.

Back pain treatment in water has been commonly used although there is little evidence about its effects. One purported advantage for exercise is the reduced loading due to the buoyant force. The purpose of this study was to compare stature change, as a marker of spinal loading, after sitting in aquatic and dry land environments. Fourteen asymptomatic volunteers had their stature measured in a precision stadiometer, before and after a bout of physical activity and during a recovery period either sitting in water (head out of water immersion; HOWI) and sitting in a chair on land (SITT). Stature loss following exercise was as expected similar in both groups (SITT=89.2+/-5.4% and HOWI=86.5+/-8.1%; p=0.33). When stature recovery was compared between the water and land environments, HOWI (102.2+/-8.7%) showed greater recovery than SITT (86.5+/-6.3%) after 30 min (p<0.05). These results suggest that HOWI facilitated more rapid stature recovery through lower spinal loading and supports use of this technique to reduce spinal loading during recovery.

Transient effects of stretching exercises on gait parameters of elderly women.

This study aimed to analyse the effects of a single stretching exercise session on a number of gait parameters in elderly participants in an attempt to determine whether these exercises can influence the risk of fall. Fifteen healthy women living in the community volunteered to participate in the study. A kinematic gait analysis was performed immediately before and after a session of static stretching exercises applied on hip flexor/extensor muscles. Results showed a significant influence of stretching exercises on a number of gait parameters, which have previously been proposed as fall predictors. Participants showed increased gait velocity, greater step length and reduced double support time during stance after performing stretching exercises, suggesting improved stability and mobility. Changes around the pelvis (increased anterior-posterior tilt and rotation range of motion) resulting from the stretching exercises were suggested to influence the gait parameters (velocity, step length and double support time). Therefore, stretching exercises were shown to be a promising strategy to facilitate changes in gait parameters related to the risk of fall. Some other gait variables related to the risk of fall remained unaltered (e.g., toe clearance). The stable pattern of segmental angular velocities was proposed to explain the stability of these unchanged gait variables. The results indicate that stretching exercises, performed on a regular (daily) basis, result in gait adaptations which can be considered as indicative of reduced fall risk. Other studies to determine whether regular stretching routines are an effective strategy to reduce the risk of fall are required.

Wheelchair propulsion: effects of experience and push strategy on efficiency and perceived exertion.

The purpose of this study was to examine the role of wheeling experience on efficiency, metabolic cost, and differentiated ratings of perceived exertion (RPEs) during synchronous and asynchronous hand-rim propulsion with varying arm frequencies. Fourteen able-bodied (AB) male participants and 8 male wheelchair sportsmen (WS) performed tests of peak oxygen consumption for both propulsion modes. Subsequently, 2 series of five 4-min sub-maximal exercise bouts were completed at an individualized velocity (60% of peak oxygen consumption). Arm frequencies consisted of the freely chosen frequency (FCF), followed by 4 counter-balanced paced trials pushing at 60%, 80%, 120%, and 140% of the FCF. Efficiency indices (gross, GE; work, WE) were determined and peripheral (RPE-P), central (RPE-C), and overall (RPE-O) RPEs were recorded. The GE (6.4% vs. 8.4%) and WE (11.3% vs. 15.1%) were significantly higher in WS than in AB (p = 0.001). Trends in the oxygen consumption, GE, and WE data were similar in both groups, propulsion mode, and arm frequency. Data suggest that 80% FCF resulted in improved efficiency for both propulsion mode and group, although the differences between those arm frequencies immediately above and below were non-significant. Lower RPE scores corresponded with higher efficiency values. Regardless of group there were significant differences (p = 0.001) between the differentiated RPE measures, whereby RPE-P was on average always the highest score (13.1) and RPE-C the lowest (11.1; RPE-O was 12.2). In conclusion, despite the anticipated differences in efficiency between the WS and AB participants, this study confirmed that psycho-physiological measures produce similar trends to physiological measures with manipulations of both arm frequency and propulsion mode.

The influence of resting period length on jumping performance.

The purpose of this study was to determine a resting interval between countermovement jumps (i.e., volleyball spikes) that allows the maintenance of maximal jumping performance. Ten male volleyball players (1.85 +/- 0.05 m, 77.2 +/- 10.6 kg, 21.6 +/- 5.3 years) performed 6 experimental jumping sessions. In the first and sixth sessions, maximal countermovement jump height was measured, followed by submaximal countermovement jumps to the point of volitional fatigue. The number of countermovement jumps was used as a reference to test the effect of rest period between volleyball spikes. From the second to fifth experimental sessions, 30 maximal volleyball spikes were performed with different resting periods (i.e., 8, 14, 17, and 20 seconds) followed by countermovement jumps. Between the 15th and 30th spikes, the blood lactate concentration and heart rate were measured. Because the performance on the first and sixth sessions was the same, no training effects were noticed. During the 8-second resting interval set, the lactate concentration increased significantly between the 15th and 30th spikes (i.e., from 3.37 +/- 1.16 mmol to 4.94 +/- 1.49 mmol); the number of countermovement jumps decreased significantly after spikes compared to those performed without a previous effort (i.e., from 23 +/- 7 jumps to 17 +/- 9 jumps); and these variables were significantly correlated (r = -0.7). On the other hand, the lactate concentration and number of countermovement jumps were stable across the other resting intervals, without a heart rate steady state. The results indicate that an adequate resting period between spikes allowed participants to achieve a lactate steady state in which the performance was maintained during the exercise. These findings show that resting intervals between 14 and 17 seconds, typical during volleyball matches, are indicated to use in volleyball spike drills due to their capacity to maintain maximal jumping performance.

The impact of increasing paraspinal muscle activity on stature recovery in asymptomatic people.

OBJECTIVE: To determine whether changes in stature recovery could be exhibited in an asymptomatic group through the use of functional electric stimulation (FES). DESIGN: A repeated-measures cohort study considering the effects of FES on stature recovery after a loaded walking task in a group of asymptomatic subjects. Each participant performed the 20-minute loaded walking task (at 10% of body mass) on 2 separate occasions followed by a 20-minute recovery period, once with FES and once without. Measurements of stature using a stadiometer were recorded throughout. SETTING: A university laboratory. PARTICIPANTS: Eight asymptomatic male volunteers (age, 29.0+/-5.1y; mass, 80.7+/-8.4kg; height, 1.81+/-0.06m) with no history of chronic low back pain (LBP) were recruited through notices in the university and local communities. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Recovery of stature was assessed via stadiometry during the postexercise unloading periods. RESULTS: Each participant experienced significantly better stature recovery (percentage of stature reduction) during the control session compared with the FES session, with mean stature recoveries of 104.6%+/-22.9% and 56.3%+/-27.4%, respectively (P=.01). CONCLUSIONS: Use of FES correlated with significant reductions in stature recovery. Elevating paraspinal muscle activity may increase compression on the intervertebral disks and therefore diminish the ability to recover the reduction in height caused by the loaded walking task. This investigation offers further support to the theory that the raised paraspinal muscle activity exhibited by persons with chronic LBP leads to reduced stature recovery.

Raised paraspinal muscle activity reduces rate of stature recovery after loaded exercise in individuals with chronic low back pain.

OBJECTIVES: To further the understanding of stature recovery in subjects with and without chronic low back pain (CLBP) and to determine the relations among stature recovery, paraspinal muscle activity, and perceived pain and disability. DESIGN: A case-control study in which stature loss and recovery were assessed in subjects with and without CLBP after a 20-minute loaded walking task (10% of body mass). Group differences in pain, disability, and paraspinal muscle activity were also assessed. SETTING: A university laboratory. PARTICIPANTS: Twenty subjects with CLBP were matched (age, sex, body mass, physical activity level) with 20 controls who were recruited through notices in the university, general community, and local Primary Care Trust. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Stature changes and integrated electromyograms of the paraspinal muscles during a loading and unloading period were assessed. RESULTS: Stature changes after loading did not differ between groups ( P <.05). Subjects with CLBP recovered significantly less stature during unloading than did the controls ( P <.05). Paraspinal muscle activity correlated negatively with stature recovery ( P <.05). Relations among stature recovery, pain, and disability were shown ( P <.05). CONCLUSIONS: The elevated paraspinal muscle activity exhibited by the CLBP group increased compression on the intervertebral disks and diminished their ability to recover the height lost through loaded exercise. Further research is required to establish whether a change in paraspinal muscle activity is associated with corresponding changes in stature recovery, and if this has any clinical implications by reducing pain and disability.