Optimizing Backrest Geometry to Minimize Interfacial Pressure Concentrations in the Mid-To-Lumbar Region During Leg Press Resistance Training

2021 ◽  
Author(s):  
Vincent Castonguay-Siu ◽  
William Taylor
Keyword(s):  
Resistance Training ◽  
Pressure Distribution ◽  
Real Time ◽  
Spinal Injury ◽  
Lumbar Region ◽  
Leg Press ◽  
Interfacial Pressure ◽  
Vertebral Bodies ◽  
Peak Pressures ◽  
Increased Pressure

Abstract The leg press is a resistance training (RT) exercise common to both weight- and powerlifting, where spine-related injuries remain prevalent. Here, the elevated loading has the potential to result in increased pressure on vertebral bodies and introduce the risk of spinal injury. This study therefore investigates back interfacial pressure under leg press loading conditions and offers design recommendations to minimize spatial pressure concentrations. A pressure mat was used to assess the back-backrest interfacial pressure distribution of 15 subjects executing RT leg-presses at 50% bodyweight, over 16 different back-support geometries. Real-time forces, knee angles, and pressures were captured. The resulting data show that more prominent (?2.1 cm) back-supports, positioned 19cm above the seat pan typically produced greater peak pressures (41.8±7.2 kPa). Conversely, less prominent supports (~0.7 cm) generally achieved lower peak pressures (with greater distribution). Our data suggest that the most prudent choice for fixed-shape backrests to best distribute interfacial pressure on leg-press devices is to incorporate shallow convex supports (~0.7 cm), and locate them away from P=19 cm. The result is surprising as this prominence location is a common ergonomic feature. If an adjustable backrest is considered, peak pressures may be reduced by up to 26±8% (9.7±3.1 kPa) compared to flat geometries.

scholarly journals Meta-Analysis Examining the Importance of Creatine Ingestion Strategies on Lean Tissue Mass and Strength in Older Adults

Nutrients ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1912
Author(s):  
Scott C. Forbes ◽  
Darren G. Candow ◽  
Sergej M. Ostojic ◽  
Michael D. Roberts ◽  
Philip D. Chilibeck
Keyword(s):  
Resistance Training ◽  
Meta Analysis ◽  
Creatine Supplementation ◽  
Strength Increase ◽  
Lean Tissue ◽  
Tissue Mass ◽  
Resistance Training Program ◽  
Lean Tissue Mass ◽  
Leg Press ◽  
Meta Analyses

Creatine supplementation in conjunction with resistance training (RT) augments gains in lean tissue mass and strength in aging adults; however, there is a large amount of heterogeneity between individual studies that may be related to creatine ingestion strategies. Therefore, the purpose of this review was to (1) perform updated meta-analyses comparing creatine vs. placebo (independent of dosage and frequency of ingestion) during a resistance training program on measures of lean tissue mass and strength, (2) perform meta-analyses examining the effects of different creatine dosing strategies (lower: ≤5 g/day and higher: >5 g/day), with and without a creatine-loading phase (≥20 g/day for 5–7 days), and (3) perform meta-analyses determining whether creatine supplementation only on resistance training days influences measures of lean tissue mass and strength. Overall, creatine (independent of dosing strategy) augments lean tissue mass and strength increase from RT vs. placebo. Subanalyses showed that creatine-loading followed by lower-dose creatine (≤5 g/day) increased chest press strength vs. placebo. Higher-dose creatine (>5 g/day), with and without a creatine-loading phase, produced significant gains in leg press strength vs. placebo. However, when studies involving a creatine-loading phase were excluded from the analyses, creatine had no greater effect on chest press or leg press strength vs. placebo. Finally, creatine supplementation only on resistance training days significantly increased measures of lean tissue mass and strength vs. placebo.

Foot Function in Patients With Surgically Treated Preaxial Polydactyly of the Foot Compared With Age- and Sex-Matched Healthy Controls

2018 ◽  
Vol 40 (4) ◽  
pp. 414-421
Author(s):  
Elise B. Burger ◽  
Shaktie A. Lalé ◽  
Steven E. R. Hovius ◽  
Christianne A. van Nieuwenhoven ◽  
Sicco A. Bus
Keyword(s):  
Pressure Distribution ◽  
Plantar Pressure ◽  
Healthy Controls ◽  
Level Of Evidence ◽  
Cross Sectional ◽  
Aesthetic Appearance ◽  
Patient Reported ◽  
Foot Function ◽  
Peak Pressures ◽  
Age And Sex

Background: Treatment of preaxial foot polydactyly, a duplication of the first ray, consists of excision of an extra ray, aiming to improve shoe fitting and aesthetic appearance, while maintaining foot function. Currently, the effect of excision on foot function and foot-related patient experiences is unclear. Methods: A cross-sectional comparison between 37 children treated for preaxial foot polydactyly and 37 age- and sex-matched healthy controls was performed. Dynamic foot function was assessed using plantar pressure measurements and static foot characteristics by physical examination. Patient-reported outcomes for foot function and footwear were evaluated, using the Oxford Ankle Foot Questionnaire for Children (score, 0-100). Results: Compared with controls, patients had significantly lower median peak pressures at the hallux (148 kPa [IQR, 98-245] vs 272 kPa [IQR, 205-381], P < .001) and significantly higher peak pressures at the second metatarsal (217 kPa [IQR, 147-338] vs 166 kPa [IQR, 141-235], P = .002) and third to fifth metatarsals (214 kPa [IQR, 147-290] vs 161 kPa [IQR, 135-235], P < .001). Additionally, patients had a more medially deviated hallux, both while seated (15 degrees (IQR, 11-20) vs 12 degrees [IQR, 10-15], P = .001) and standing (20 degrees [IQR, 15-26] vs 18 degrees [IQR, 15-20], P = .001). No significant correlation between peak pressure distribution and hallux deviation was found. Patients reported minimal problems with foot function (87.5 [IQR, 64.6-100]), but distinct problems with footwear use (50.0 [IQR, 25.0-100]). Conclusion: Patients with surgically treated preaxial foot polydactyly had a substantially altered plantar pressure distribution with more lateral foot progression than healthy controls. Although an increased hallux deviation was not related to altered foot function, it seemed to be the reason for the patient-perceived problems with footwear. Level of Evidence: Level III, comparative series.

Measurement of Seat Pressure Distributions

1987 ◽  
Vol 29 (5) ◽  
pp. 563-575 ◽  
Author(s):  
Delia Treaster ◽  
W. S. Marras
Keyword(s):  
Pressure Distribution ◽  
Video Signals ◽  
Optical Reflection ◽  
Pressure Distributions ◽  
Experimental Apparatus ◽  
Image Digitization ◽  
Novel Method ◽  
Measurement And Evaluation ◽  
Peak Pressures ◽  
Chair Design

Knowledge of seating pressures is important for proper chair design. This study demonstrates the usefulness of a new methodology for measuring pressure distributions. It refines and advances an optical-reflection technique introduced several years ago. In this way precise quantitative measures of the pressure distribution can be obtained. Video image digitization, which converts analog video signals to digital ones, provided data in a form that could be easily submitted for computer analysis. Additionally, a novel method of analysis is presented that allows for the measurement and evaluation of the distribution of seated pressures, rather than peak pressures alone. A preliminary experiment with eight subjects was conducted to demonstrate the validity of the experimental apparatus and the data treatment.

Negligible Effects of β-Hydroxy-β-Methylbutyrate Free Acid and Calcium Salt on Strength and Hypertrophic Responses to Resistance Training: A Randomized, Placebo-Controlled Study

2019 ◽  
Vol 29 (5) ◽  
pp. 505-511 ◽  
Author(s):  
Aline C. Tritto ◽  
Salomão Bueno ◽  
Rosa M.P. Rodrigues ◽  
Bruno Gualano ◽  
Hamilton Roschel ◽  
...  
Keyword(s):  
Resistance Training ◽  
Body Mass ◽  
Muscle Soreness ◽  
Calcium Salt ◽  
Free Acid ◽  
Time Effect ◽  
Controlled Study ◽  
Cross Sectional ◽  
Repetition Maximum ◽  
Leg Press

This study evaluated the effects of β-hydroxy-β-methylbutyrate free acid (HMB-FA) and calcium salt (HMB-Ca) on strength, hypertrophy, and markers of muscle damage. In this randomized, double-blind, placebo-controlled study, 44 resistance-trained men (age: 26 ± 4 years; body mass: 84.9 ± 12.0 kg) consuming ≥1.7 g·kg−1·day−1 of protein received HMB-FA (3 g/day; n = 14), HMB-Ca (3 g/day; n = 15), or placebo (PL; cornstarch, 3 g/day; n = 15) for 12 weeks, while performing a periodized resistance training program. Before and after intervention, lean body mass (measured with dual X-ray absorptiometry), maximal dynamic strength (one-repetition maximum), knee extension maximal isometric strength (maximal voluntary isometric contraction [MVIC]), cross-sectional area (measured with ultrasound), and muscle soreness were assessed. MVIC was also measured 48 hr after the first and the last training sessions. All groups increased lean body mass (main time effect: p < .0001; HMB-FA: 1.8 ± 1.8 kg; HMB-Ca: 0.8 ± 1.4 kg; PL: 0.9 ± 1.4 kg), cross-sectional area (main time effect: p < .0001; HMB-FA: 6.6 ± 3.8%; HMB-Ca: 4.7 ± 4.4%; PL: 6.9 ± 3.8%), one-repetition maximum bench press (main time effect: p < .0001; HMB-FA: 14.8 ± 8.4 kg; HMB-Ca: 11.8 ± 7.4 kg; PL: 11.2 ± 6.6 kg), MVIC (main time effect: p < .0001; HMB-FA: 34.4 ± 39.3%; HMB-Ca: 32.3 ± 27.4%; PL: 17.7 ± 20.9%) after the intervention, but no differences between groups were shown. HMB-FA group showed greater leg press strength after the intervention than HMB-Ca and PL groups (Group × Time interaction: p < .05; HMB-FA: 47.7 ± 31.2 kg; HMB-Ca: 43.8 ± 31.7 kg; PL: 30.2 ± 20.9 kg). MVIC measured 48 hr after the first and the last sessions showed no attenuation of force decline with supplementation. Muscle soreness following the first and last sessions was not different between groups. The authors concluded that neither HMB-Ca nor HMB-FA improved hypertrophy or reduced muscle damage in resistance-trained men undergoing resistance training ingesting optimal amounts of protein. HMB-FA but not HMB-Ca resulted in a statistically significant yet minor improvement on leg press one-repetition maximum.

scholarly journals Cold water immersion attenuates anabolic signaling and skeletal muscle fiber hypertrophy, but not strength gain, following whole-body resistance training

2019 ◽  
Vol 127 (5) ◽  
pp. 1403-1418 ◽  
Author(s):  
Jackson J. Fyfe ◽  
James R. Broatch ◽  
Adam J. Trewin ◽  
Erik D. Hanson ◽  
Christos K. Argus ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Resistance Training ◽  
Protein Content ◽  
Muscle Fiber ◽  
Cold Water ◽  
Water Immersion ◽  
Cold Water Immersion ◽  
Post Exercise ◽  
Leg Press ◽  
Before And After

We determined the effects of cold water immersion (CWI) on long-term adaptations and post-exercise molecular responses in skeletal muscle before and after resistance training. Sixteen men (22.9 ± 4.6 y; 85.1 ± 17.9 kg; mean ± SD) performed resistance training (3 day/wk) for 7 wk, with each session followed by either CWI [15 min at 10°C, CWI (COLD) group, n = 8] or passive recovery (15 min at 23°C, control group, n = 8). Exercise performance [one-repetition maximum (1-RM) leg press and bench press, countermovement jump, squat jump, and ballistic push-up], body composition (dual X-ray absorptiometry), and post-exercise (i.e., +1 and +48 h) molecular responses were assessed before and after training. Improvements in 1-RM leg press were similar between groups [130 ± 69 kg, pooled effect size (ES): 1.53 ± 90% confidence interval (CI) 0.49], whereas increases in type II muscle fiber cross-sectional area were attenuated with CWI (−1,959 ± 1,675 µM2 ; ES: −1.37 ± 0.99). Post-exercise mechanistic target of rapamycin complex 1 signaling (rps6 phosphorylation) was blunted for COLD at post-training (POST) +1 h (−0.4-fold, ES: −0.69 ± 0.86) and POST +48 h (−0.2-fold, ES: −1.33 ± 0.82), whereas basal protein degradation markers (FOX-O1 protein content) were increased (1.3-fold, ES: 2.17 ± 2.22). Training-induced increases in heat shock protein (HSP) 27 protein content were attenuated for COLD (−0.8-fold, ES: −0.94 ± 0.82), which also reduced total HSP72 protein content (−0.7-fold, ES: −0.79 ± 0.57). CWI blunted resistance training-induced muscle fiber hypertrophy, but not maximal strength, potentially via reduced skeletal muscle protein anabolism and increased catabolism. Post-exercise CWI should therefore be avoided if muscle hypertrophy is desired. NEW & NOTEWORTHY This study adds to existing evidence that post-exercise cold water immersion attenuates muscle fiber growth with resistance training, which is potentially mediated by attenuated post-exercise increases in markers of skeletal muscle anabolism coupled with increased catabolism and suggests that blunted muscle fiber growth with cold water immersion does not necessarily translate to impaired strength development.

scholarly journals Ultraflexible and transparent electroluminescent skin for real-time and super-resolution imaging of pressure distribution

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Byeongmoon Lee ◽  
Ji-Young Oh ◽  
Hyeon Cho ◽  
Chul Woong Joo ◽  
Hyungsoo Yoon ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Real Time ◽  
Super Resolution ◽  
Resolution Imaging

scholarly journals Effect of neuromuscular resistance training on the performance of 5-km runners

Kinesiology ◽  
2020 ◽  
Vol 52 (1) ◽  
pp. 64-71
Author(s):  
Miller P. Guimarães ◽  
Yuri A.C. Campos ◽  
Hiago L.R. de Souza ◽  
Gaspar P. da Silva ◽  
Claudio Hernández-Mosqueira ◽  
...  
Keyword(s):  
Resistance Training ◽  
Body Height ◽  
Time Trial ◽  
Distance Runners ◽  
Fat Percentage ◽  
Leg Press ◽  
Baseline Values ◽  
Incremental Protocol ◽  
Fourth Session ◽  
Training Protocol

The study aimed to identify the effect of a neuromuscular resistance training protocol (NRTP) on the performance of 5-km distance runners. This study included 18 male runners (age=29.3±3.2 years, fat percentage=11.3±2.6%, body height=1.77±.04 m, body mass=73.4±4.4 kg, time in 5 km=20.6±2.4 min, training years=4.3±0.7 years). First, volunteers were anthropometrically evaluated, and they performed one-repetition maximum (1RM) 45º leg press (LP) strength test. Second, they performed an incremental protocol in the 45º LP to acquire the electromyographic threshold. Third, they completed a 5-km time trial run (5 km basal). In the fourth session, they performed NRTP in LP. And fifth, the 5-km time trial run was performed at 30 min, 48 h, 96 h, and 144 h post the NRTP intervention. A significant decrease (p≤.05) was observed when baseline values were compared with post 30 min and post 48 h (p=.02 and p=.04, respectively). However, there were significant positive differences in performance (p=.04 for time) when baseline values and post 144 h were analyzed. Therefore, it is concluded that the NRTP can be used by 5-km distance runners to improve their performance with a break of one week between the intervention and test.

scholarly journals Effects of Creatine Supplementation during Resistance Training Sessions in Physically Active Young Adults

Nutrients ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1880
Author(s):  
Scotty Mills ◽  
Darren G. Candow ◽  
Scott C. Forbes ◽  
J. Patrick Neary ◽  
Michael J. Ormsbee ◽  
...  
Keyword(s):  
Young Adults ◽  
Resistance Training ◽  
Vertical Jump ◽  
Training Session ◽  
Creatine Supplementation ◽  
Muscle Thickness ◽  
Training Set ◽  
Physically Active ◽  
Leg Press ◽  
Total Body

The purpose was to examine the effects of creatine supplementation during resistance training sessions on skeletal muscle mass and exercise performance in physically active young adults. Twenty-two participants were randomized to supplement with creatine (CR: n = 13, 26 ± 4 yrs; 0.0055 g·kg−1 post training set) or placebo (PLA: n = 9, 26 ± 5 yrs; 0.0055 g·kg−1 post training set) during six weeks of resistance training (18 sets per training session; five days per week). Prior to and following training and supplementation, measurements were made for muscle thickness (elbow and knee flexors/extensors, ankle plantarflexors), power (vertical jump and medicine ball throw), strength (leg press and chest press one-repetition maximum (1-RM)) and muscular endurance (one set of repetitions to volitional fatigue using 50% baseline 1-RM for leg press and chest press). The creatine group experienced a significant increase (p < 0.05) in leg press, chest press and total body strength and leg press endurance with no significant changes in the PLA group. Both groups improved total body endurance over time (p < 0.05), with greater gains observed in the creatine group. In conclusion, creatine ingestion during resistance training sessions is a viable strategy for improving muscle strength and some indices of muscle endurance in physically active young adults.

scholarly journals Once a Week Resistance Training Improves Muscular Strength in Breast Cancer Survivors: A Randomized Controlled Trial

2019 ◽  
Vol 18 ◽  
pp. 153473541987974 ◽  
Author(s):  
Wanderson Divino Nilo dos Santos ◽  
Amilton Vieira ◽  
Claudio Andre Barbosa de Lira ◽  
João Felipe Mota ◽  
Paulo Gentil ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Body Composition ◽  
Resistance Training ◽  
Muscle Strength ◽  
Cancer Survivors ◽  
Muscular Strength ◽  
Breast Cancer Survivors ◽  
Bench Press ◽  
Post Intervention ◽  
Leg Press

Background: Exercise has been shown to reduce adverse outcomes related to breast cancer. However, the rate of adherence to physical exercise is very low among breast cancer survivors (BCS). This study investigated the effects of high supervision ratio resistance training (RT), once a week for 8 weeks, on changes in body composition and muscular strength in BCS. Methods: Twenty-five female BCS undergoing hormone therapy were randomized into resistance training group (TG, n = 12) or control (CG, n = 13) group. The TG performed 8 weeks of supervised RT, with 1 trainer per volunteer, once a week. Body composition was evaluated by dual-energy X-ray absorptiometry, and muscle strength was evaluated by 10 repetition maximum (10 RM) for leg press (45°) and bench press exercises. A 1-way analysis of variance was used to compare within-group effects at pre- and post-intervention. An analysis of covariance test was used to compare post-intervention values, using pre-intervention measures as covariates. The effect size (ES) was calculated by Cohen’s d. Results: The TG improved muscle strength in 10 RM leg press (45°; Δ 33.75 ± 11.51 kg, P = .02; ES = 0.96) and bench press (Δ 4.08 ± 1.83 kg, P = .01; ES = 1.15). Adherence to training was more than 99%. Changes in body composition were not detected. There were no changes in the CG for any assessment. Conclusion: Once-weekly supervised RT could be an alternative to increase the adherence to exercise and improve muscular strength in BCS.

The effects of pre-exhaustion, exercise order, and rest intervals in a full-body resistance training intervention

2014 ◽  
Vol 39 (11) ◽  
pp. 1265-1270 ◽  
Author(s):  
James Peter Fisher ◽  
Luke Carlson ◽  
James Steele ◽  
Dave Smith
Keyword(s):  
Resistance Training ◽  
Training Programme ◽  
Training Intervention ◽  
Control Group ◽  
Rest Interval ◽  
Leg Press ◽  
Body Resistance ◽  
Different Order ◽  
Composition Changes ◽  
Full Body

Pre-exhaustion (PreEx) training is advocated on the principle that immediately preceding a compound exercise with an isolation exercise can target stronger muscles to pre-exhaust them to obtain greater adaptations in strength and size. However, research considering PreEx training method is limited. The present study looked to examine the effects of a PreEx training programme. Thirty-nine trained participants (male = 9, female = 30) completed 12 weeks of resistance training in 1 of 3 groups: a group that performed PreEx training (n = 14), a group that performed the same exercise order with a rest interval between exercises (n = 17), and a control group (n = 8) that performed the same exercises in a different order (compound exercises prior to isolation). No significant between-group effects were found for strength in chest press, leg press, or pull-down exercises, or for body composition changes. Magnitude of change was examined for outcomes also using effect size (ES). ESs for strength changes were considered large for each group for every exercise (ranging 1.15 to 1.62). In conclusion, PreEx training offers no greater benefit to performing the same exercises with rest between them compared with exercises performed in an order that prioritises compound movements.

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