Box Lifting Research Articles

The effect of heat mitigation strategies on thermoregulation and productivity during simulated occupational work in the heat in physically active young men.

To investigate heat stress mitigation strategies on productivity and thermoregulatory responses during simulated occupational work in the heat. Thirteen physically active men (age, 25 ± 4 years; body mass,77.8 ± 14.7 kg; VO2peak, 44.5 ± 9.2 ml·kg-1·min-1) completed five randomized-controlled trials in a hot environment (40°C, 40% relative humidity). Each trial was 4.5 h in duration to simulate an outdoor occupational shift. Thermoregulatory responses (heart rate, HR; rectal temperature, Trec; mean skin temperature, Tsk), perceptual responses (rating of perceived exertion, RPE; thermal sensation; thermal comfort; fatigue) and productivity outcomes (box lifting repetitions, time to exhaustion) were examined in the following heat mitigation strategy interventions: (1) simulated solar radiation with limited fluid intake [SUN]; (2) simulated solar radiation with no fluid restrictions [SUN + H2O]; (3) shade (no simulated solar radiation during trial) with no fluid restrictions [SHADE + H2O]; (4) shade and cooling towels during rest breaks with no fluid restrictions [COOL + H2O]; and (5) shade with cooling towels, cooling vest during activity with no fluid restrictions [COOL + VEST + H2O]. [COOL + VEST + H2O] had lower Trec compared to [SUN] [p = 0.004, effect size(ES) = 1.48], [SUN + H2O] (p < 0.001, ES = -1.87), and [SHADE + H2O] (p = 0.001, ES = 1.62). Average Tsk was lower during the treadmill and box lifting activities in the [COOL + VEST + H2O] compared to [SUN] (p < 0.001, ES = 7.92), [SUN + H2O] (p < 0.001,7.96), [SHADE + H2O] (p < 0.001), and [COOL + H2O] (p < 0.001, ES = 3.01). There were performance differences during the [COOL + VEST + H2O] (p = 0.033) and [COOL + H2O] (p = 0.023) conditions compared to [SUN] during phases of the experimental trial, however, there were no differences in total box lifting repetitions between trials (p > 0.05). Our results suggest that during a simulated occupational shift in a laboratory setting, additional heat mitigation strategies ([COOL + VEST + H2O] and [COOL + H2O]) reduced physiological strain and improved box lifting performance to a greater degree than [SUN]. These differences may have been attributed to a larger core to skin temperature gradient or reduction in fatigue, thermal sensation, and RPE during [COOL + H2O] and [COOL + VEST + H2O]. These data suggest that body cooling, hydration, and "shade" (removal of simulated radiant heat) as heat stress mitigation strategies should be considered as it reduces physiological strain while producing no additional harm.

A Novel Passive Shoulder Exoskeleton Using Link Chains and Magnetic Spring Joints.

Work-related musculoskeletal disorders represent a major occupational disability issue, and 53.4% of these disorders occur in the back or shoulders. Various types of passive shoulder exoskeletons have been introduced to support the weight of the upper arm and work tools during overhead work, thereby preventing injuries and improving the work environment. The general passive shoulder exoskeleton is constructed with rigid links and joints to implement shoulder rotation, but there exists a challenge to align with the flexible joint movements of the human shoulder. Also, a force-generating part using mechanical springs require additional mechanical components to generate torque similar to the shoulder joint, resulting in increased overall volume and inertia to the upper arm. In this study, we propose a new type of passive shoulder exoskeleton that uses magnetic spring joint and link chain. The redundant degrees of freedom in the link chains enables to follow the shoulder joint movement in the horizontal direction, and the magnetic spring joint generates torque without additional parts in a compact form. Conventional exoskeletons experience a loss in the assisting torque when the center of shoulder rotation changed during arm elevation. Our exoskeleton minimizes the torque loss by customizing the installation height and initial angle of the magnetic spring joint. The performances of the proposed exoskeleton were verified by an electromyographic evaluation of shoulder-related muscles in overhead work and box lifting task.

Measurement and Evaluation of Potential Ergonomic Hazards in the Packing Area of PT Tirta Investama Klaten Factory

PT Tirta Investama Klaten Factory is a company that produces bottled drinking water. Most production activities use machines, but there are still activities carried out manually, namely in the packing area during box lifting activities. Box lifting activities that are carried out repeatedly over a certain period can potentially cause occupational diseases, namely musculoskeletal disorders. After conducting initial interviews with workers, it was discovered that workers in the packing area felt pain and tingling in their bodies. Based on these problems, it is necessary to measure and evaluate potential ergonomic hazards to identify potential health and worker protection problems due to ergonomic hazards. The method used SNI 9011:2021, a tool for measuring and evaluating potential ergonomic hazards in the workplace, and used QEC (Quick Exposure Checklist) to measure posture load from two points of view. The research results showed that the box lifting activity had the worst percentage exposure value of 76.14% and the worst ERF score of 7 (hazardous conditions). Apart from having an awkward posture, the results showed that symptoms of musculoskeletal disorders experienced by workers were also caused by factors such as age and length of service.

Divisibility on point counting over finite Witt rings

Let Fq denote the finite field of q elements with characteristic p. Let Zq denote the unramified extension of the p-adic integers Zp with residue field Fq. In this paper, we investigate the q-divisibility for the number of solutions of a polynomial system in n variables over the finite Witt ring Zq/pmZq, where the n variables of the polynomials are restricted to run through a box lifting Fqn. It turns out that in general the answers do depend upon the box chosen. Based on the addition operation of Witt vectors, we prove a q-divisibility theorem for any box of low algebraic complexity, including the simplest Teichmüller box. This extends the classical Ax-Katz theorem over finite field Fq (the case m=1). Taking q=p to be a prime, our result extends and improves a recent theorem of Grynkiewicz for the unweighted case.

Functionally relevant physical exercises as an objective measure of clinical improvement in pediatric chronic pain.

This exploratory study demonstrates the application of functionally relevant physical exercises (FRPE) to objectively assess physical functioning among children with chronic pain. Intensive interdisciplinary pain treatment (IIPT) focuses on functional improvements as a primary outcome. FRPEs aim to enhance clinical assessments and monitoring by providing relevant data for physical and occupational therapies. Children enrolled in three weeks of IIPT provided data for study. They completed two self-report measures of functioning (Lower Extremity Functioning Scale [LEFS] and Upper Extremity Functioning Index [UEFI]), measure of pain intensity, and six separate FRPEs (box carry, box lifts, floor to stand, sit to stand, step ups, and modified six-minute walk test). Data from 207 participants aged 8-20 years old were analyzed. Upon admission, over 91% of children could perform each FRPE at some level to provide clinicians with a baseline assessment of functional strength. Following IIPT, all children were able to complete FRPEs. Overall, children reported statistically significant gains in functioning on all subjective reports and FRPEs (p's < 0.001). Spearman correlations demonstrated that LEFS and UEFI were weakly to moderately correlated to all FRPEs at admission (r's between.43-.64, p's < 0.001 and.36-.50, p's < 0.01 respectively). Correlations between all subjective and objective measures were comparatively lower at discharge. FRPEs appear to serve as good objective measures of strength and mobility for children with chronic pain, measuring variability across patients and change over time, which is unique from subjective data gathered via self-report. Due to face validity and objective measurement of functioning, from a clinical practice perspective, FRPEs provide meaningful information to support initial assessment, treatment planning, and patient monitoring. This study offers initial support for a novel measurement method that is easily administered and replicated to effectively measure functional improvement in children with chronic pain.

The effect of clinically elevated body mass index on physiological stress during manual lifting activities.

Individuals with a body mass index (BMI) classified as obesity constitute 27.7% of U.S. workers. These individuals are more likely to experience work-related injuries. However, ergonomists still design work tasks based on the general population and normal body weight. This is particularly true for manual lifting tasks and the calculation of recommended weight limits (RWL) as per National Institute of Occupational Safety & Health (NIOSH) guidelines. This study investigates the effects of BMI on indicators of physiological stress. It was hypothesized that, for clinically elevated BMI individuals, repeated manual lifting at RWL would produce physiological stress above safety limits. A repetitive box lifting task was designed to measure metabolic parameters: volume of carbon dioxide (VCO2) and oxygen (VO2), respiratory exchange ratio (RER), heart rate (HR), and energy expenditure rate (EER). A two-way ANOVA compared metabolic variables with BMI classification and gender, and linear regressions investigated BMI correlations. Results showed that BMI classification represented a significant effect for four parameters: VCO2 (p < 0.001), VO2 (p < 0.001), HR (p = 0.012), and EER (p < 0.001). In contrast, gender only had a significant effect on VO2 (p = 0.014) and EER (p = 0.017). Furthermore, significant positive relationships were found between BMI and VCO2 (R2 = 59.65%, p < 0.001), VO2 (R2 = 45.01%, p < 0.001), HR (R2 = 21.86%, p = 0.009), and EER (R2 = 50.83%, p < 0.001). Importantly, 80% of obese subjects exceeded the EER safety limit of 4.7 kcal/min indicated by NIOSH. Indicators of physiological stress are increased in clinically elevated BMI groups and appear capable of putting these individuals at increased risk for workplace injury.

Feedback on Trunk Movements From an Electronic Game to Improve Postural Balance in People With Nonspecific Low Back Pain: Pilot Randomized Controlled Trial.

BackgroundPostural balance is compromised in people with low back pain, possibly by changes in motor control of the trunk. Augmenting exercising interventions with sensor-based feedback on trunk posture and movements might improve postural balance in people with low back pain.ObjectiveWe hypothesized that exercising with feedback on trunk movements reduces sway in anterior-posterior direction during quiet standing in people with low back pain. Secondary outcomes were lumbar spine and hip movement assessed during box lift and waiter bow tasks, as well as participant-reported outcomes. Adherence to the exercising intervention was also examined.MethodsA randomized controlled trial was conducted with the intervention group receiving unsupervised home exercises with visual feedback using the Valedo Home, an exergame based on 2 inertial measurement units. The control group received no intervention. Outcomes were recorded by blinded staff during 4 visits (T1-T4) at University Hospital Zurich. The intervention group performed 9 sessions of 20 minutes in the 3 weeks between T2 and T3 and were instructed to exercise at their own convenience between T3 and T4. Postural balance was assessed on a force platform. Lumbar spine and hip angles were obtained from 3 inertial measurement units. The assessments included pain intensity, disability, quality of life, and fear of movement questionnaires.ResultsA total of 32 participants with nonspecific low back pain completed the first assessment T1, and 27 (84%) participants were randomized at T2 (n=14, 52% control and n=13, 48% intervention). Intention-to-treat analysis revealed no significant difference in change in anterior-posterior sway direction during the intervention period with a specified schedule (T2-T3) between the groups (W=99; P=.36; r=0.07). None of the outcomes showed significant change in accordance with our hypotheses. The intervention group completed a median of 61% (55/90; range 2%-99%) of the exercises in the predefined training program. Adherence was higher in the first intervention period with a specified schedule.ConclusionsThe intervention had no significant effect on postural balance or other outcomes, but the wide range of adherence and a limited sample size challenged the robustness of these conclusions. Future work should increase focus on improving adherence to digital interventions.Trial RegistrationClinicalTrials.gov NCT04364243; https://clinicaltrials.gov/ct2/show/NCT04364243International Registered Report Identifier (IRRID)RR2-10.2196/26982

Characterization of Occupational Lifting Patterns with Exposure Variation Analysis. Cross-sectional Workplace Study among Blue-Collar Workers.

To investigate and characterize the influence of sex, age, muscle strength, and cardiovascular fitness on manual lifting patterns using exposure variation analysis (EVA) during a full working day among blue-collar workers. Muscular activity (surface electromyography [sEMG]) of the thigh, low-back, and shoulder was measured throughout the working day in 173 employees with manual lifting tasks from 14 workplaces. Relative sEMG loading was expressed as % of maximal voluntary contraction (MVC). As an additional and more practically oriented analysis, calibration of load from standardized box lifts (5, 10, 20, and 30 kg) identified corresponding sEMG values in kg. Using an EVA 'lifting periods' of [1 to 5, >5 to 10, >10 to 20, >20 to 30, and >30] kg in time intervals [0 to 0.5, >0.5 to 1, >1 to 2, >2 to 5, >5 to 10, and >10] s were identified. Arm elevation and back inclination were measured using accelerometers. Females and older workers (≥50 years) primarily used the thighs for lifting and were exposed to more frequent thigh muscle 'lifting periods' of varying duration and load and performed more thigh lifts >30 kg and >60% of MVC compared with males and younger workers (P < 0.05). Females had less brief shoulder lifting periods and more work with bent back >30° than the males (P < 0.05), whereas stronger workers performed more work with elevated arm >60° and >90° than workers with low muscle strength (P < 0.05). However, besides a single difference where workers with lower cardiovascular fitness were exposed to more light (1-5 kg) and moderate duration (5-10 s) trapezius loading, the number of lifting periods was not affected by muscle strength nor cardiovascular fitness (P > 0.05). This EVA demonstrated sex- and age-related differences in exposure to lifting periods involving shoulder and thigh muscles.

Short-term effects of the Auxivo LiftSuit during lifting and static leaning

Back support exosuits can support workers in physically demanding jobs by reducing muscle load, which could reduce risk of work-related musculoskeletal disorders. This paper presents a two-session evaluation of a commercial exosuit, the Auxivo LiftSuit 1.1. In session 1, 17 participants performed single repetitions of lifting and static leaning tasks with and without the LiftSuit. In session 2, 10 participants performed 50 box lifting repetitions with and without the LiftSuit. In session 1, the exosuit was considered mildly to moderately helpful, and reduced erector spinae and middle trapezius electromyograms. In session 2, the exosuit was not considered helpful, but reduced the middle trapezius electromyogram and trunk and thigh ranges of motion. These effects are likely due to placement of elastic elements and excessive stiffness at the hips. Overall, the LiftSuit appears suboptimal for long-term use, though elastic elements on the upper back may reduce muscle activation in future exosuit designs.

A comparison of augmented feedback and didactic training approaches to reduce spine motion during occupational lifting tasks

Manual handling training may be improved if it relied on the provision of individualized, augmented feedback about key movement features. The purpose of this study was to compare the reduction in sagittal spine motion during manual lifting tasks following two training approaches: didactic (DID) and augmented feedback (AUG). Untrained participants (n = 26) completed lifting tests (box, medication bag, and paramedic backboard) and a randomly-assigned intervention involving 50 practice box lifts. Lifting tests were performed immediately before and after training, and one-week after interventions. Both groups exhibited reductions in spine motions immediately and one-week after the interventions. However, the AUG intervention group elicited significantly greater reductions in 5 of 12 between-group comparisons (3 tasks × 4 spine motion variables). The results of the current study support the use of augmented feedback-based approaches to manual handling training over education-based approaches.

Biomechanical Evaluation of the Effect of Minimally Invasive Spine Surgery Compared with Traditional Approaches in Lifting Tasks.

Fusion of spinal vertebrae can be accomplished by different surgical approaches. We investigated Traditional Open Spine Surgery (TOSS) versus Minimally Invasive Spine Surgery (MISS). While TOSS sacrifices spine muscles originating or inserting on the affected vertebrae, MISS seeks to minimize the approach-related morbidity and preserve the tendon attachments of the muscles in the area. We captured 3-D motions of the full body of one healthy subject performing a variety of 10 kg box lifting operations representing activities-of-daily-living that are likely to challenge the spine biomechanically. The motion data were transferred to a full-body biomechanical model with a detailed representation of the biomechanics of the spine, and simulations of the internal spine loads and muscle forces were performed under a baseline configuration and muscle configurations typical for TOSS respectively MISS for the cases of L3/L4, L4/L5, L5/S1, L4/S1 and L3/L5 fusions. The computational model was then used to investigate the biomechanical differences between surgeries. The simulations revealed that joint reaction forces are more affected by both surgical approaches for lateral lifting motions than for sagittal plane motions, and there are indications that individuals with fused joints, regardless of the approach, should be particularly careful with asymmetrical lifts. The MISS and TOSS approaches shift the average loads of different muscle groups in different ways. TOSS generally leads to higher post-operative muscle loads than MISS in the investigated cases, but the differences are smaller than could be expected, given the differences of surgical technique.

A Collision Avoidance Algorithm for Human Motion Prediction Based on Perceived Risk of Collision: Part 2-Application

Occupational Application Digital human models have been widely used for occupational assessments to reduce potential injury risk, such as automotive assembly lines, box lifting, and in the mining industry. Human motion prediction is one of the important capabilities in digital human models, and collision avoidance is involved in human motion prediction. An algorithm proposed earlier was implemented for human motion prediction, and simulated results were found to have a good correlation with the experimental studies. Use of this algorithm can help ensure that human motion is predicted realistically, and thus can impact the accuracy of injury risk assessments. Background: With any type of human movement, there is the potential for a collision with other objects. In addition to the objects presented in the environment surrounding one’s body and surrounding the objects to be manipulated, one's own body can become an obstacle. Therefore, consideration of the methods available for avoiding obstacles is necessary to comprehensively describe the way human movements are planned. Purpose: This paper evaluates a collision avoidance algorithm for human motion prediction based on the perceived risk of collision, specifically the application to human motion prediction. Method: Human motion prediction is formulated as an optimization problem with dynamic effort as the cost function, and the perceived risk of collision is considered as one constraint among other constraints. Performance using the new formulation was compared to observed performance from an experiment. Result: Based on the results, the new formulation can account for the suboptimal behavior observed in real subjects while still optimizing biomechanical cost. The predicted motion is much more realistic compared with that from purely biomechanically optimized formulation. Application: The developed collision avoidance algorithm can be applied to optimization-based manual movement prediction in which obstacles need to be navigated.

The role of Self-Efficacy in Chronic Pain—A Case Report Relating Motivation During The COVID-19 Pandemic and a Patient With Chronic Pain

Research ObjectivesTo analyze patient outcomes and traditional physical therapy interventions for chronic low back back, and discuss the benefits of incorporating self-efficacy techniques to improve patient independence.DesignRetrospective case report.SettingOutpatient physical therapy setting.Participants48-year-old female with complaints of chronic low back pain that has increased significantly over the last six months due to the societal consequences of COVID-19. The patient's past medical history included mild arthritis of her spine. The medications she was using for pain included Naproxen, and the patient also found relief with Salonpas pain relief patches.Interventions1. Trunk flexion AAROM, x 10 repetitions, by rolling swiss ball forward on plinth to promote a stretch of the lower back and eliminate fear of mobility.2. interferential electrical stimulation to low back to decrease pain x 10 min3. bilateral dynamic hip strengthening on hip abduction machine with 45#, 10 reps x 3 sets each4. Functional training such as proper lifting mechanics, 5 repetitions of box lifting5. physiological components aimed to improve self-efficacyMain Outcome Measures1.numerical pain rating scale2. Modified Oswestry Low Back Pain Disability QuestionnaireResultsThe patient's pain improved throughout the 6 weeks that she was seen at physical therapy. This is reflected on her scores on the NPRS. Her baseline pain rating was 9.5/10 and by 6 weeks her score decreased to 3/10. The patient also showed improvements on the Modified Oswestry Disability Index, as seen by a decrease from 42% disability to 10% disability. Improvements were seen in the patient's bed mobility, lumbar flexion AROM, bilateral hip strength, and lower abdominal strength.ConclusionsThis case is an example of someone with chronic low back pain that prior to the pandemic, had enough self efficacy to manager her condition independently. Interventions during physical therapy focused on traditional manual and therapeutic exercise principles as well as physiological components aimed to improve her self-efficacy.Author(s) DisclosuresI declare that I have no relevant or material financial interests that relate to the research described in this paper”.

A Collision Avoidance Algorithm for Human Motion Prediction Based on Perceived Risk of Collision: Part 1-Model Development

OCCUPATIONAL APPLICATIONS Digital human models have been widely used in occupational biomechanics assessments to prevent potential injury risks, such as automotive assembly lines, box lifting, patient repositioning, and the mining industry. Motion prediction is one of the important capabilities in digital human models, and collision avoidance is involved in human motion prediction. We propose an algorithm that will ensure human motions are predicted realistically, and finally, use of this algorithm could help enhance the accuracy of injury risk assessments using digital human models.

Novel thoraco-lumbo-sacral corset design increases Biering-Sorensen back endurance and alters knee and ankle angles during a box lifting task

Research investigating lumbosacral corset designs and their effects are limited and conflicting. The objective was to compare thoraco-lumbo-sacral support corsets (polyester/nylon: TLSSC-poly and neoprene: TLSSC-neo) with a traditional model (TRAD) and Control. Twenty male, university-aged, healthy, recreationally active, participants performed Biering-Sorensen back endurance (BS) test and box lifting tasks (BL:30 repetitions using 20% body mass). Lower and upper erector spinae and hamstrings electromyography (EMG); trunk-hip, knee, and ankle kinematics as well as endurance time were monitored. With BL, the TLSSC-poly (121.4°±17.9) exhibited 1.9% (p = 0.01), 2.7% (p = 0.003), and 3.7% (p = 0.0003) greater knee flexion than TRAD (119.1°±17.5), TLSSC-neo (116.8°±17.4) and Control (120.1°±17.6) respectively. The TLSSC-poly (101.9°± 8.9) demonstrated significant 3.5% (p = 0.005), 2.2% (p = 0.002) and 1.4% (p = 0.01) greater dorsiflexion than TRAD (103.4°±8.7), TLSSC-neo (104.2°±9.8) and Control (105.7°±7.2) respectively. With BS, TLSSC-poly (137.4-s±31.2, 9.7%, p = 0.018) and TLSSC-neo (133.8-s±32.3, 9.2%, p = 0.006) exhibited significantly longer durations than Control (124.8-s±29.8). Relevance to industry: The TLSSC increased BS endurance and TLSSC-poly increased BL knee and ankle angles, possibly providing benefits for workers, with repeated actions over a full work day.

Between-session reliability of skin marker-derived spinal kinematics during functional activities

BackgroundSkin marker-based analysis of functional spinal movement is a promising method for quantifying longitudinal effects of treatment interventions in patients with spinal pathologies. However, observed day-to-day changes might not necessarily be due to a treatment intervention, but can result from errors related to soft tissue artifacts, marker placement inaccuracies or biological day-to-day variability. Research questionHow reliable are skin marker-derived three-dimensional spinal kinematics during functional activities between two separate measurement sessions? MethodsTwenty healthy adults (11 females/9 males) were invited to a movement analysis laboratory for two visits separated by 7–10 days. At each visit, they performed various functional activities (i.e. sitting, standing, walking, running, chair rising, box lifting and vertical jumping), while marker trajectories were recorded using a skin marker-based 10-camera optical motion capture system and used to calculate sagittal and frontal plane spinal curvature angles as well as transverse plane segmental rotational angles in the lumbar and thoracic regions. Between-session reliability for continuous data and discrete parameters was determined by analyzing systematic errors using one sample T-tests as well as by calculating intraclass correlation coefficients (ICCs) and minimal detectable changes (MDCs). Results and SignificanceThe analysis indicated high relative consistency for sagittal plane curvature angles during all activities, but not for frontal and transverse plane angles during walking and running. MDCs were mostly below 15°, with relative values ranging between 10 % and 750 %. This study provides important information that can serve as a basis for researchers and clinicians aiming at investigating longitudinal effects of treatment interventions on spinal motion behavior in patients with spinal pathologies.

Three-dimensional asymmetric maximum weight lifting prediction considering dynamic joint strength.

In this study, the three-dimensional (3D) asymmetric maximum weight lifting is predicted using an inverse-dynamics-based optimization method considering dynamic joint torque limits. The dynamic joint torque limits are functions of joint angles and angular velocities, and imposed on the hip, knee, ankle, wrist, elbow, shoulder, and lumbar spine joints. The 3D model has 40 degrees of freedom (DOFs) including 34 physical revolute joints and 6 global joints. A multi-objective optimization (MOO) problem is solved by simultaneously maximizing box weight and minimizing the sum of joint torque squares. A total of 12 male subjects were recruited to conduct maximum weight box lifting using squat-lifting strategy. Finally, the predicted lifting motion, ground reaction forces, and maximum lifting weight are validated with the experimental data. The prediction results agree well with the experimental data and the model's predictive capability is demonstrated. This is the first study that uses MOO to predict maximum lifting weight and 3D asymmetric lifting motion while considering dynamic joint torque limits. The proposed method has the potential to prevent individuals' risk of injury for lifting.

Factors affecting spine loading in a box lifting task: a digital human modelling study

This paper presents a digital human modelling (DHM) study of a box-lifting task considering human physical characteristics (i.e., gender and percentile) and task requirements (i.e., posture and force). Two response variables are considered: compression force on L4/L5 and the tension on right/left Latissimus Dorsi muscle. Multivariate analysis of variance (MANOVA) was used to analyse the data. Results showed that lower back compression force is positively correlated with Latissimus Dorsi muscle tension (r = 0.94). Moreover, the 95th percentile male in standing position experienced the highest compression force on the lower back; however, both males and females had similar muscle tension.

The Effects Of Mode Of Rehydration On Stress Hormone Respsonse To Subsequent Maximal Intensity Exercise In The Heat.

PURPOSE: Endocrine response to strenuous exercise in the heat can serve as an indicator of the amount of strain the body is experiencing. Previous intravenous (IV) versus oral rehydration studies found no difference cortisol (CORT) response between modes of rehydration, but mixed norepinephrine (NOR) response with ORAL during an exercise-heat challenge (EHC). The purpose of this study was to examine the effects of mode of rehydration on the stress-hormone response to a subsequent EHC that more closely mimics a real-life athletic situation utilizing three traditional modes of rehydration ad libitum (ADL), IV and ORAL and combined half IV and half ORAL (I+O) fluids of identical volume. METHODS: Ten healthy, non-smoking, active men (age 23.3 ± 1.1 y; height, 177.8 ± 2.8 cm; body mass, 81.4 ± 1.3 kg; body fat, 11.0 ± 1.0%; O2max, 58.8 ± 1.3 ml·kg-1·min-1) completed four trials consisting of dehydration by -4% body mass, rehydration to -2% body mass, and an EHC comprised of 25 min of running at 60% O2max, a maximal effort 0.5 mile run, five minutes of rest and five min of self-paced repetitive box lifting (RBL). Plasma catecholamines [epinephrine (EPI) and NOR] and CORT were analyzed at baseline, post-exercise dehydration, immediately before EHC (EHCPRE), immediately-post 0.5 mile run (EHC30), immediately-post RBL (EHCIP), and 15 minutes post-RBL. Data was analyzed with a two-way repeated measures ANOVA or Student’s t-test, p< 0.05. RESULTS: Catecholamine response was not significantly different between modes of rehydration, but significantly increased during EHC (EHCPRE - EPI 0.52±0.44 pmol·L-1, NOR 2.64±0.89 nmol·L-1; EHC30 - EPI 3.59±1.89 pmol·L-1, NOR 21.66±7.42 nmol·L-1; EHCIP - EPI 1.31±0.84 pmol·L-1, NOR 15.45±6.63 nmol·L-1). CORT response was significantly lower during I+O (EHCPRE: 451.8±118.5 nmol·L-1, EHCIP 505.4±237.9 nmol·L-1) compared to all other trials (EHCPRE 567.1±240.5 nmol·L-1, EHCIP - 603.6±270.1 nmol·L-1). CONCLUSIONS: These results suggest a synergistic effect of I+O on plasma CORT concentration resulting in reduced adreno-cortical response. It is possible the I+O treatment resulted in reduced hormonal response or increased removal rate due to a combination of oropharyngeal response and rapid plasma volume restoration since stress was controlled across conditions.

Effect of a novel low volume, high intensity concurrent training regimen on recruit fitness and resilience

ObjectivesTo determine the effect of a novel low volume high intensity concurrent training regimen and warm-up on physiological performance and musculoskeletal injury in Australian recruits. DesignControlled longitudinal intervention. MethodsMilitary recruits completed 12 weeks of either experimental (EXP: n=78, 6-8RM resistance loads, and high intensity intervals) or basic military (CON: n=69, usual practice) matched for total sessions and time. Endurance (3.2km 22kg-load carriage, V˙O2 peak, multi-stage fitness test (MSFT)), 1RM strength and local muscle endurance (bench, squat, box-lift and push-ups) and power (squat jump) were assessed at Weeks 1,6,12. Body composition, physical activity (PAC·min−1) and heart rate reserve (HRR%), were assessed at Weeks 2,7,9. Musculoskeletal injury and mechanism were recorded. Two-way repeated measures ANOVA interaction (group×time), mean difference and effect size (ES) are reported p≤0.05. ResultsA significant interaction over 12 weeks was observed for load carriage (ES −0.30), squat jump (ES 0.65), V˙O2 peak (ES 0.58), MSFT (ES 0.41), push-ups (ES 0.26), 1RM bench (ES 0.26), squat (ES 1.05) and box lift (ES 0.27) in EXP compared to CON. At Week 12 significantly greater squat (38.9kg), MSFT (2.1mL·kg−1·min−1), and faster load carriage (49.9s) was observed in EXP than CON, but no difference in body composition. EXP had a lower PAC·min−1 (641.1±63.1) but higher HRR% (21.8±4.0) compared to CON. EXP had a lower number of injuries (6) compared to CON (17). ConclusionsThe inclusion of compound-specific resistance exercise and high intensity intervals improved physical function and was associated with reduced musculoskeletal injury.