Effects of 22 °C muscle temperature on voluntary and evoked muscle properties during and after high-intensity exercise

2007 ◽  
Vol 32 (6) ◽  
pp. 1043-1051 ◽  
Author(s):  
Eric J. Drinkwater ◽  
David G. Behm
Keyword(s):  
High Intensity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Contractile Properties ◽  
Muscle Temperature ◽  
Plantar Flexors ◽  
Muscle Properties ◽  
Time To Peak ◽  
Cohen’S D ◽  
Cohen's D

The purpose of this study was to investigate the effect of 22 °C local muscle temperature of intact human plantar flexors performing fatiguing contractions on evoked and voluntary contractile properties before and after fatigue. Twelve subjects were tested on plantar flexor voluntary torque, percent muscle activation derived from twitch interpolation, integrated electromyographic (iEMG) activity, and evoked torque and temporal characteristics of maximal twitch and tetanic stimulations before fatigue and 1, 5, and 10 min after intermittent, high-intensity, isometric fatigue under both normothermic and hypothermic conditions. Hypothermic and normothermic changes between time points were analysed by repeated-measures analysis of variance. Normothermic fatigue induced small to large effects (Cohen’s d: 0.29–3.06) on voluntary and evoked contractile properties, whereas most effects of unfatigued hypothermia were limited to rate-dependent processes (Cohen’s d: 0.78–1.70). Most tetanic properties were potentiated 1 min after normothermic fatigue, but remained unchanged by hypothermic fatigue, resulting in significant differences between the two conditions. Soleus iEMG significantly declined 1 min after normothermic fatigue (–29%), but not after hypothermic fatigue. Twitch torque was potentiated by 29% one minute after fatigue while normothermic, but was potentiated by 46% while hypothermic; rate of twitch torque development and time to peak twitch were potentiated by 39% and 10% while normothermic, but 89% and 28% while hypothermic. Although voluntary contractile properties are generally impaired soon after normothermic fatigue, most were not after hypothermic fatigue. Furthermore, evoked contractile properties were generally higher 1 min after hypothermic fatigue. We conclude that the hypothermic condition slows the recovery of potentiated evoked contractile properties back to baseline values.

Effects of fatigue duration and muscle type on voluntary and evoked contractile properties

1997 ◽  
Vol 82 (5) ◽  
pp. 1654-1661 ◽  
Author(s):  
D. G. Behm ◽  
D. M. M. St-Pierre
Keyword(s):  
Muscle Activation ◽  
Compound Muscle Action Potential ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Plantar Flexors ◽  
Muscle Type ◽  
M Wave ◽  
Time To Peak ◽  
Muscle Action Potential

Behm, D. G., and D. M. M. St-Pierre. Effects of fatigue duration and muscle type on voluntary and evoked contractile properties. J. Appl. Physiol. 82(5): 1654–1661, 1997.—The effects of fatigue duration and muscle type on voluntary and evoked contractile properties were investigated with an isometric, intermittent, submaximal fatigue protocol. Four groups performed contractions of the plantar flexors and quadriceps at various intensities to produce long (LDF; 19 min 30 s)- and short-duration fatigue (SDF; 4 min 17 s). The LDF group had a significantly greater decrease in muscle activation than did the SDF group (12 vs. 5.8%) during recovery, although there was no difference in the impairment of maximum voluntary contraction force beyond 30 s of recovery. The significant decrease in the compound muscle action potential of the LDF group (M-wave amplitude; 14.7%) contrasted with the M-wave potentiation of the SDF group (15.7%), suggesting changes in membrane excitation may affect LDF. The quadriceps group performing contractions at 50% MVC experienced a smaller decrease in agonist electromyograph activity than did other groups, indicating both muscle and fatigue duration specificity. Impairments in excitation-contraction coupling were indicated by changes in quadriceps peak twitch and time to peak twitch while decreases in PF M-wave amplitudes suggested a disruption of membrane potentials. Results suggest that fatigue mechanisms may be duration (activation, half relaxation time) or muscle specific (electromyograph, twitch torque) or a combination of both (M wave, time to peak twitch torque).

scholarly journals Auriculotherapy to reduce anxiety and pain in nursing professionals: a randomized clinical trial

2017 ◽  
Vol 25 (0) ◽  
Author(s):  
Leonice Fumiko Sato Kurebayashi ◽  
Ruth Natalia Teresa Turrini ◽  
Talita Pavarini Borges de Souza ◽  
Carolina Felicio Marques ◽  
Renata Tavares Franco Rodrigues ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Clinical Trial ◽  
Randomized Clinical Trial ◽  
Nursing Staff ◽  
Repeated Measures ◽  
Statistical Significance ◽  
Cohen’S D ◽  
Pain Visual Analog Scale ◽  
Cohen's D

RESUMEN Objectives: to evaluate the effectiveness of the auricular protocol (APPA) in reducing pain and anxiety and improving the quality of life of the nursing staff of a hospital. Method: randomized clinical trial with an initial sample of 180 professionals divided into 4 groups Control (G1), Seed (G2), Needle (G3) and Tape (G4). The evaluation instruments were the State-Trait Anxiety Inventory, Pain Visual Analog Scale and Quality of Life instrument, applied at the start and after five and 10 sessions (five weeks). Descriptive statistics, analysis of variance (ANOVA) and Cohen's d Index were used in the analysis. Results: there was a statistical difference (p < 0.05) for anxiety according to the repeated measures ANOVA, with better results for the G3 in the final assessment (Cohen's d index 1.08/17% reduction). There was a reduction of pain of 36% in G3 and 24% in G2 and a 13% increase in the mental aspect of quality of life for the G3, although without statistical significance. Conclusion: the APPA protocol reduced the anxiety levels of nursing staff after 10 sessions. Further studies are, however, suggested with new populations and in different contexts so that the results can be confirmed. RBR-5pc43m.

scholarly journals Small Step Frequency Changes Due to Footwear Condition Have No Effect on Running Economy

2018 ◽  
Vol 02 (02) ◽  
pp. E41-E45 ◽  
Author(s):  
Joe Warne ◽  
Kieran Moran ◽  
Giles Warrington
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Running Economy ◽  
Small Step ◽  
Step Frequency ◽  
Cohen’S D ◽  
Running Shoes ◽  
Frequency Changes ◽  
Cohen's D

AbstractThe aim of this study is to examine if small increases to step frequency associated with minimal footwear can influence Running Economy (RE). Twelve club-level runners with eight weeks of minimal footwear experience were recruited (age, 41±9 years; stature, 177.2±10.4 cm; body mass, 72.6±10.2 kg; V˙O2max, 52.1±7.5 mL·min−1·kg−1). Two 6-min RE tests, one in minimal footwear and one in conventional running shoes were performed at 11 km·h−1. Two more 6-min tests were completed during which step frequency was controlled using a metronome at the cadence of the opposite footwear condition (RErevSF). Comparisons were completed between the same footwear using repeated measures ANCOVA. The increase in step frequency for minimal footwear vs. conventional running shoes was 7.3±2.3 steps per minute (3.9% difference; 95% CI of difference [5.87 to 8.80 steps/min]; p≤0.001; Cohen’s d=0.70). No significant differences were identified between RE and RErevSF for minimal footwear (40.72±4.08 vs. 41.09±4.19 mL·min−1·kg−1; 95% CI of difference [–1.71 to 0.97]; p=0.55; Cohen’s d=0.09), or conventional running shoes (42.04±4.68 vs. 41.74±5.09 mL·min−1·kg−1; 95% CI of difference [–0.78 to 1.37]; p=0.55; Cohen’s d=0.06). Small changes in step frequency (~4%) did not have any significant impact on RE.

scholarly journals HRV‐Monitoring im Rahmen eines vierwöchigen High‐Intensity Intervalltrainings

2020 ◽  
Author(s):  
Christoph Schneider
Keyword(s):  
High Intensity ◽  
Cohen’S D ◽  
Allen Test ◽  
Cohen's D

EINLEITUNG. Das Monitoring von Belastungs‐ und Erholungsreaktionen im Sport gilt mittlerweile als zentralesInstrument im Prozess der Optimierung und Individualisierung von Trainingsmaßnahmen. Die Messungder Herzfrequenz (HR) ‐variabilität (HRV) stellt hier ein vielversprechendes Monitoringtool dar,welches einen Einblick in Aktivität und Regulationsmechanismen des kardial‐autonomen Nervensystems(ANS) liefert. Ziel der Studie ist die Evaluation eines HRV‐Monitorings im Rahmen eines vierwöchigenHigh‐Intensity Intervalltrainings (HIT) hinsichtlich der Fähigkeit Belastungs‐ und Erholungsreaktionensowie Leistungsveränderungen abzubilden.METHODIK. 12 trainierte Probanden aus intermittierenden Sportarten absolvierten einen 4‐wöchigen,periodisierten HIT‐Zyklus mit jeweils 3 Trainingseinheiten pro Woche. Die maximale und submaximaleLeistungsfähigkeit wurde mittels Stufentests auf dem Laufband vor (Baseline) sowie zwei (Post 1) undneun Tage (Post 2) nach der Interventionsphase ermittelt. Der allgemeine Erholungsstatus (KEB) wurdean allen Test‐ und Trainingstagen erfragt. Begleitend, sowie zwei Wochen vor und nach der Intervention,wurden täglich 6‐minütige HRV‐Ruhemessungen nach dem Aufstehen durchgeführt und anschließendmittels gleitendem 7 Tage‐Mittelwert analysiert.ERGEBNISSE. Das Training löste moderate bis starke (Cohen’s d = ‐1,12 bis ‐1,25) Ermüdungserscheinungen(KEB) in den Interventionswochen 1 und 3 (likely bis most likely) aus. Die maximale Leistungsfähigkeitzeigte klare Verbesserungen (d = 0,20 bis 0,41) an Post 1 und Post 2 (likely bis most likely), wobei diesubmaximale Leistungsfähigkeit tendenziell (possibly) an Post 2 gering (d = 0,21 bis 0,23) erhöht war. DerHRV‐Parameter Ln rMSSD/RR war an Post 2 gering (d = ‐0,40) verringert (likely). Die drei Einzelfallanalysenzeigten erheblich divergierende ANS‐Reaktionen bei den betrachteten Athleten, welche sich vergleichbarüberdurchschnittlich in ihrer submaximalen und maximalen Leistungsfähigkeit verbesserten.SCHLUSSFOLGERUNG. Ein HRV‐Monitoring auf Grundlage täglicher Ruhemessungen und gleitender 7 Tage‐Mittelwertsbildung ist auf Gruppenebene nicht in der Lage die beobachteten Belastungs‐ und Erholungsreaktionenoder die Leistungsverbesserungen abzubilden. Im Rahmen von Einzelfallanalysenscheint die HRV potenziell nützliche Informationen hinsichtlich individueller Adaptationsverläufen liefernzu können, welche möglicherweise eine Individualisierung und Optimierung von Trainingsplanungund ‐steuerung ermöglichen. Dennoch stehen Aufwand und Nutzen, sowohl auf Gruppen‐ als auch aufEinzelfallebene, in einem deutlichen Defizitverhältnis. Ein HRV‐Monitoring ist derzeit unter Anwendungder etablierten Methoden in vergleichbaren Settings nicht empfehlenswert.

Strength and Contractile Adaptations in the Human Triceps Surae after Isotonic Exercise

1993 ◽  
Vol 2 (2) ◽  
pp. 104-114 ◽  
Author(s):  
Crayton L. Moss ◽  
Scott Grimmer
Keyword(s):  
Relaxation Time ◽  
Repeated Measures ◽  
Peak Force ◽  
Contractile Properties ◽  
Triceps Surae ◽  
Type I ◽  
Muscle Twitch ◽  
Time To Peak ◽  
High Repetition ◽  
Isotonic Exercise

The purpose of this study was to determine whether twitch contractile properties and strength of the triceps surae could be altered by 8 weeks of low-repetition or high-repetition isotonic exercise. Subjects were randomly assigned to either the low- or high-repetition group. Before- and after-training measurements were recorded for strength and contractile properties. The contractile variables of the muscle twitch were latency, time to peak force, peak force, half-contraction time, and half-relaxation time. Strength measurements were determined utilizing a one repetition maximal (1-RM) heel-raise testing device. A two-way ANOVA with repeated measures was used to test the effect of training on each variable. Both groups showed a significant increase in 1-RM and half-relaxation time and a decrease in electrical stimulation current after the 8-week training period. It was concluded that if high-repetition exercises develop slow-twitch Type I muscle fibers and low-repetition exercises develop fast-twitch Type II fibers, training programs must be designed specifically according to the desired outcome.

Hip- and Trunk-Muscle Activation Patterns During Perturbed Gait

2011 ◽  
Vol 20 (3) ◽  
pp. 287-295 ◽  
Author(s):  
Justin M. Stanek ◽  
Todd A. McLoda ◽  
Val J. Csiszer ◽  
A.J. Hansen
Keyword(s):  
Outcome Measures ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Kinetic Chain ◽  
Time To Peak ◽  
Muscle Activation Patterns ◽  
Unexpected Perturbation

Context:Selected muscles in the kinetic chain may help explain the body’s ability to avert injury during unexpected perturbation.Objective:To determine the activation of the ipsilateral rectus femoris (RF), gluteus maximus (MA), gluteus medius (ME), and contralateral external obliques (EO) during normal and perturbed gait.Design:Single-factor, repeated measures.Setting:University research laboratory.Participants:32 physically active, college-age subjects.Intervention:Subjects walked a total of 20 trials the length of a 6.1-m custom runway capable of releasing either side into 30° of unexpected inversion. During 5 trials, the platform released into inversion.Main Outcome Measures:Average, peak, and time to peak EMG were analyzed across the 4 muscles, and comparisons were made between the walking trials and perturbed trials.Results:Significantly higher average and peak muscle activity were noted for the perturbed condition for RF, MA, and EO. Time to peak muscle activity was faster during the perturbed condition for the EO.Conclusion:Rapid contractions of selected postural muscles in the kinetic chain help explain the body’s reaction to unexpected perturbation.

scholarly journals The Impact of a Rotating Balance Platform on Leg Neuromuscular Activity in Healthy Young Adults

2021 ◽  
pp. 22
Author(s):  
Keyword(s):  
Muscle Contraction ◽  
Lower Limb ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Time To Peak ◽  
Contraction Duration ◽  
Tracking Tasks ◽  
Balance Rehabilitation ◽  
The Impact ◽  
Balance Board

Balance is a functional activity that must be implemented in every type of rehabilitation for the back and lower extremities’ injury and pathology. With issues in these regions, balance is lessened, requiring exercises that enhance the patient’s stability. Purpose: To determine the impact of activities on a rotating balance platform with tracking tasks for lower limb muscle activation. Method: Twenty-five participants performed seven tasks on a balance board with a fixed middle fulcrum. For each trial, activation of the gastrocnemius and tibialis anterior muscles was recorded using surface electromyography. Upon examination of the EMG data, the following variables were quantified: time to peak muscle activation, time to decay of muscle contraction, and time of muscle contraction duration. Results: A repeated measures ANOVA revealed that TA exhibited significant modifications (P<0.001) with less time to peak, duration, and decay, whereas GA only notably compensated (P<0.001) with shorter duration and decay. Conclusion: For subjects with balance alterations due to slower nerve conduction or muscle weakness in the lower limb, we suggest incorporating activities with rotational movements on the balance board, where muscle activation is challenged due to surface and tracking activities. When endurance is prescribed, front-to-back tasks contribute to prolonged muscle activation. Balance rehabilitation should consider muscle activation timing with tracking tasks for more precise and targeted muscle execution.

scholarly journals The effects of passive stretching plus vibration on strength and activation of the plantar flexors

2016 ◽  
Vol 41 (9) ◽  
pp. 917-923 ◽  
Author(s):  
Jonathan D. Miller ◽  
Trent J. Herda ◽  
Michael A. Trevino ◽  
Eric M. Mosier
Keyword(s):  
Plantar Flexion ◽  
Muscle Length ◽  
Peak Torque ◽  
Plantar Flexors ◽  
Cohen’S D ◽  
Passive Stretching ◽  
Before And After ◽  
Cohen's D ◽  
Voluntary Contractions ◽  
Musculotendinous Stiffness

This study examined the effects of passive stretching only (PS+CON) and passive stretching with the addition of continuous vibration (VIB) during post-passive stretching tests (PS+VIB) on peak torque (PT), percent voluntary inactivation (%VI), single stimulus twitch torque (TTSINGLE), and doublet stimuli twitch torque (TTDOUBLET) of the plantar flexors at a short (20° plantar flexion (PF)) and long muscle length (15° dorsiflexion (DF)). Fourteen healthy men (age = 22 ± 3 years) performed isometric maximal voluntary contractions at PF and DF, and passive range of motion (PROM) assessments before and after 8 × 30-s passive stretches without (PS+CON) or with VIB (PS+VIB) administered continuously throughout post-passive stretching tests. The passive properties of the muscle tendon unit were assessed pre- and post-passive stretching via PROM, passive torque (PASSTQ), and musculotendinous stiffness (MTS) measurements. PT, TTSINGLE, and TTDOUBLET decreased, whereas, %VI increased following passive stretching at PF and DF (P < 0.05) with no significant differences between PS+CON and PS+VIB. PASSTQ and MTS decreased while PROM increased post-passive stretching during both trials (P < 0.05). The stretching-induced force/torque deficit and increases in %VI were evident following passive stretching at short and long muscle lengths. Although not statistically significant, effect size calculations suggested large and moderate differences in the absolute changes in PT (Cohen’s d = 1.14) and %VI (Cohen’s d = 0.54) from pre- to post-passive stretching between treatments, with PS+VIB having greater decreases of PT and higher %VI than PS+CON. The decrement in PT following passive stretching may be primarily neural in origin.

scholarly journals Physical Demands in Three Different Basketball Competitions Played By the Same Under-18 Players

2021 ◽  
Vol 10 (2) ◽  
pp. 59-64
Author(s):  
Hugo Salazar ◽  
◽  
Franc Garcia ◽  
Luka Svilar ◽  
Julen Castellano ◽  
...  
Keyword(s):  
Confidence Intervals ◽  
Effect Size ◽  
High Intensity ◽  
External Load ◽  
Training Process ◽  
Physical Demands ◽  
Cohen’S D ◽  
Basketball Coaches ◽  
Cohen's D

The goal of this study was to compare the physical demands of the same team in three different basketball com- petitions (EBA league (EBA), U18 regional league (U18L), and a U18 international tournament (U18T)) during the same season. Data from eleven U18 players (age: 16.92 ± 0.67 years) were collected using inertial movement units. As external load variables, Player Load (PL), accelerations (ACC), decelerations (DEC), changes of direction (COD), and jumps (JUMP) were expressed in their total (t) and high intensity (h) values. The analysis of variances (ANOVA) and effect size (ES, Cohen’s d) with their respective 90% confidence intervals were applied to identify differences between the competitions. U18T showed the highest values in PL, tACC, tDEC, hDEC, tCOD, tJUMP, and hJUMP (small to moderate ES). However, the hACC and hCOD values were greater in EBA (small ES) than in U18L and U18T. In conclusion, all three competitions presented different external load demands for the same group of players. This data could help basketball coaches to optimize the training process based on the competition in which their team plays. Furthermore, data could also indicate the most suitable competition for players’ development.

scholarly journals Impact of Combined Theory-Based Intervention on Psychological Effects and Physical Activity among Chinese Adolescents

2020 ◽  
Vol 17 (9) ◽  
pp. 3026
Author(s):  
Yao Zhang ◽  
Yi Yin ◽  
Jianxiu Liu ◽  
Ming Yang ◽  
Zeshi Liu ◽  
...  
Keyword(s):  
Physical Activity ◽  
Repeated Measures ◽  
Intervention Group ◽  
Control Group ◽  
Seventh Grade ◽  
Exercise Frequency ◽  
Psychological Constructs ◽  
Cohen’S D ◽  
School Day ◽  
Cohen's D

Purpose: The current study was intended to assess the effect of a facilitated behavioral intervention based on the extended theory of planned behavior (TPB) on psychological constructs and physical activity among adolescents over a period of eight weeks. Methods: Students (n = 51, 12 ± 0.3 years of age) in the seventh grade at a junior middle school in China were randomly assigned to two groups: the intervention group (n = 24) and the control group (n = 27). Both groups were pre- and post-tested with the related psychological constructs of the extended TPB, along with behavioral measures of the Physical Activity Scale and ActiGraph accelerometer (model wGT3X-BT). The intervention group took part in 45 min classes once per week for 8 weeks, including five indoor theoretical courses and three outdoor basketball matches. The control group was not required to make any change to their normal school day. Also, 2 × 2 repeated measures analysis of variance (ANOVA) was conducted to compare the differences between the two groups, and then t-test was employed to compare the independent and paired differences. Results: Significant increases in pre–post subjective norms (SN) (p = 0.041, Cohen’s d = 0.62), perceived behavior control (PBC) (p = 0.023, Cohen’s d = 0.72), exercise intention (EI) (p = 0.043, Cohen’s d = 0.61), and self-efficacy (SE) (p = 0.035, Cohen’s d = 1.36) were observed in the intervention group. In addition, participants in the intervention group increased their exercise frequency (p < 0.001, Cohen’s d = 1.25) and intensity (p = 0.028, Cohen’s d = 0.68), especially their time spent on light intensity physical activity (light-PA%; p = 0.031, Cohen’s d = 0.68), and their percentage of sedentary time (SB%) was also reduced (from 68% ± 10% to 58% ± 7%, p < 0.001, Cohen’s d = 1.17). Furthermore, the intervention group showed significantly better performance in PBC (p = 0.032, Cohen’s d = 0.62), EI (p < 0.001, Cohen’s d = 1.32), SE (p < 0.001, Cohen’s d = 1.15), SB% (p < 0.001, Cohen’s d = 1.22), light-PA% (p < 0.001, Cohen’s d = 1.12), and total physical activity (TPA) (p = 0.015, Cohen’s d = 0.72) compared to the control group at the post-test. No significant pre post differences were observed for any psychological or behavioral variables in the control group, except for exercise frequency, but the values were still lower than those in the intervention group after the 8-week intervention (3.70 ± 0.72 versus 3.92 ± 0.83). Conclusion: The combined theory-based intervention was effective at improving psychological constructs and physical activity among seventh-grade adolescents in 8 weeks.

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