Isometric Quadriceps Force Research Articles

A comparison of the effects of sheep's milk and cow's milk on recovery from eccentric exercise.

When consumed after eccentric exercise, cow's milk has been shown to improve recovery and alleviate symptoms of exercise induced muscle damage. Although currently less commercially available than cow's milk, sheep's milk may offer similar or greater benefits for recovery as it is higher in protein and energy; however, the effect of sheep's milk in any exercise context has not been explored. This study compared the effects of a sheep's milk beverage and a cow's milk beverage on recovery from strenuous eccentric exercise. Additionally, the effects of each beverage on satiety and gastrointestinal comfort were assessed. Ten healthy males completed baseline measures of perceived muscle soreness and maximal voluntary concentric, eccentric, and isometric quadriceps force of one leg before completing 200 maximal eccentric knee extensions on an isokinetic dynamometer. Measures were repeated 0.5, 24, 48 and 72 h post-eccentric exercise. After 0.5 h measures, participants consumed either 450 ml of chocolate flavored sheep's milk or chocolate flavored cow's milk. Following a washout period, participants completed a second trial on the contralateral leg and consumed the other beverage. Additionally, a satiety and gastrointestinal comfort questionnaire was completed before and after each beverage was consumed. Eccentric exercise brought about a significant decrease in muscle function over time (all P < 0.012). No difference between treatments (all P > 0.097) was found. Measures of muscle soreness increased over time (all P < 0.002), however no difference was observed between treatments (all P > 0.072). Only sheep's milk altered perceived satiety, however, only the response to "How full do you feel" differed between treatments (P = 0.04). The results of this study suggest that consuming sheep's milk may provide similar benefits as cow's milk when recovering from exercise-induced muscle damage. While these findings provide initial support for the use of sheep's milk in a muscle recovery context, further research is warranted to confirm these findings. Given its superior nutritional profile, greater impact on satiety and lower environment impact, sheep's milk may be a more efficient post-exercise recovery beverage, compared to cow's milk.

The one-minute sit-to-stand test: A practical tool for assessing functional exercise capacity in patients with COPD in routine clinical practice.

Background: Chronic obstructive pulmonary disease (COPD) is associated with a reduced exercise capacity. Although several field tests for exercise capacity have been modified for non-standard settings, i.e. outside the hospital clinic or pulmonary rehabilitation center, their uptake remains limited. Objectives: To assess the test-retest reliability, constuct validity and responsiveness of the one-minute sit-to-stand test (1'STST) adopted in clinical practice among patients with COPD and to confirm the earlier established minimal important difference (MID) of three repetitions. Methods: Patients with COPD performed two 1'STSTs, two 6-minute walk tests (6MWT), an isometric quadriceps force (QF) measurement, a cardiopulmonary exercise test (CPET), and a seven-day physical activity (PA) measurement before and after threemonths of pulmonary rehabilitation (PR). An Intraclass Correlation Coefficient (ICC) evaluated the agreement between two 1'STSTs. Pearson Correlation examined the association between the 1'STST and other physical measurements, and their changes following PR. A receiver operating characteristic (ROC) curve was constructed using a 30-meter increment in the 6MWT as cut-off to identify responders. Results: The 1'STST demonstrated good reliability (Δ0.9 ± 4.0 repetitions, p = .13; ICC = 0.79). The 1'STST was moderately correlated with the 6MWT (r = 0.57, p < .0001), VO2max (r = 0.50, p = .0006) and maximal work rate (r = 0.52, p = .0003). Weak correlations were observed with QF (r = 0.33, p = .03) and step count (r = 0.38, p = .013). The 1'STST improved after PR (∆ = 3.6 ± 6.4 repetitions, p = .0013) and changes correlated moderately with changes in the 6MWT (r = 0.57, p = .002), QF (r = 0.48, p = .003) and VO2max (r = 0.41, p = .014). A cut-off of three repetitions demonstrated a 71% accuracy in identifying responders to a rehabilitation program. Conclusion: The 1'STST is a valuable alternative to evaluate exercise capacity in patients with COPD when more expensive and time-consuming tests are unavailable.

Reliability, responsiveness, and validity of handheld dynamometry for assessing quadriceps strength in total knee arthroplasty

Purpose To determine the reliability, responsiveness, validity, and agreement of handheld dynamometry, relative to electromechanical dynamometry, for assessing quadriceps strength surrounding total knee arthroplasty. Methods Fifty-six patients (48% female) undergoing total knee arthroplasty were assessed prior to surgery and at 2 and 6 weeks following surgery. Maximum isometric quadriceps force was assessed at each time point by handheld dynamometry and electromechanical dynamometry. Within-session test–retest reliability was determined by intraclass correlation coefficient (ICC). Standard error of measurement and relative standard error (RSE) values were calculated. Standardized response means were used to describe responsiveness. Pearson's correlations examined construct validity. Agreement was assessed by the Bland–Altman method. Results Both handheld dynamometry and electromechanical dynamometry demonstrated excellent test–retest reliability (ICC >0.90) and RSE (<15%). Both methods were responsive, with large postoperative standardized response means of 1.57 (handheld dynamometry) and 1.37 (electromechanical dynamometry). Pearson's correlations were moderate to strong. The Bland–Altman analysis revealed underestimation of force by handheld dynamometry, although this effect was diminished in the early postoperative period. Conclusions Our results suggest handheld dynamometry is a promising tool for monitoring quadriceps strength in patients pre- and post-total knee arthroplasty. IMPLICATIONS FOR REHABILITATION This study provides evidence of high reliability and responsiveness of handheld dynamometry for assessing quadriceps strength throughout a clinically relevant time frame for patients with total knee arthroplasty. There is construct validity of handheld dynamometry for measuring quadriceps strength, with moderate to high correlations between handheld dynamometry and electromechanical dynamometry, both pre- and post-total knee arthroplasty. Rehabilitation professionals should be aware that handheld dynamometry and electromechanical dynamometry do not agree in terms of the force measurement itself; particularly at higher force values, handheld dynamometry underestimates force output relative to electromechanical dynamometry. Overall, this study supports the use of handheld dynamometry for monitoring quadriceps strength in clinical settings for patient with total knee arthroplasty.

Validity and reliability of strain gauge measurement of volitional quadriceps force in patients with COPD.

This study investigated the validity and reliability of fixed strain gauge measurements of isometric quadriceps force in patients with chronic obstructive pulmonary disease (COPD). A total cohort of 138 patients with COPD were assessed. To determine validity, maximal volitional quadriceps force was evaluated during isometric maximal voluntary contraction (MVC) manoeuvre via a fixed strain gauge dynamometer and compared to (a) potentiated non-volitional quadriceps force obtained via magnetic stimulation of the femoral nerve (twitch (Tw); n = 92) and (b) volitional computerized dynamometry (Biodex; n = 46) and analysed via correlation coefficients. Test–retest and absolute reliability were determined via calculations of intra-class correlation coefficients (ICCs), smallest real differences (SRDs) and standard errors of measurement (SEMs). For this, MVC recordings in each device were performed across two test sessions separated by a period of 7 days (n = 46). Strain gauge measures of MVC demonstrated very large correlation with Tw and Biodex results (r = 0.86 and 0.88, respectively, both p < 0.0001). ICC, SEM and SRD were numerically comparable between strain gauge and Biodex devices (ICC = 0.96 vs. 0.93; SEM = 8.50 vs. 10.54 N·m and SRD = 23.59 vs. 29.22 N·m, respectively). The results support that strain gauge measures of quadriceps force are valid and reliable in patients with COPD.

Community-Based Progressive Aquatic Exercise for the Management of Knee Osteoarthritis

Background: We examined the feasibility and eectiveness of a community-based progressive aquatic exercise program for com- munity dwelling older adults, with moderate to severe knee osteoarthritis (OA). Objectives: The purposes of this study were to 1, assess the eects of a progressive aquatic exercise program on the walking ability, stair climbing ability, quadriceps muscle strength, as well as self-reported symptoms, function, and quality of life in community dwelling adults with moderate to severe knee OA and; 2, assess the feasibility of a community-based aquatic program for community dwelling adults with knee OA. Methods: Seventeen volunteers (12 women (x = 61.1 years) and 5 men (x = 69.0 years)) participated in a progressive 8 - 10 week aquatic exercise program, consisting of 20 - 24, 1-hour sessions. Outcome measures, acquired twice before beginning the exercise protocol as well as after 4 and 8 weeks of exercise, included the Knee Injury and Osteoarthritis outcome score (KOOS) instrument, a 2 minute walk test (2MWT), a 10 step stair climb for time, and an isometric knee extension strength assessment. Results: Significant improvements were detected in 2 MWT, 10 step stair climb, right quadriceps isometric force development, and the KOOS symptoms and stiness subscale. Significant improvement was found on KOOS function subscales between baseline test- ing sessions and maintained at follow-up. Non-significant improvements were identified in left quadriceps isometric force devel- opment, KOOS pain, and KOOS quality of life. Conclusions: These data suggest that a community-based, progressive aquatic exercise program is feasible and results in measur- able improvements in function without worsening symptoms. Further study is warranted to investigate the impact of a longer program and the role of aquatic exercise in the long-term management of patients with knee OA.

Aerobic or Resistance Training and Pulse Wave Velocity in Kidney Transplant Recipients: A 12-Week Pilot Randomized Controlled Trial (the Exercise in Renal Transplant [ExeRT] Trial)

Cardiovascular disease remains the leading cause of death in kidney transplant recipients. This pilot study examined the potential effect of aerobic training or resistance training on vascular health and indexes of cardiovascular risk in kidney transplant recipients. Single-blind, randomized, controlled, parallel trial. 60 participants (mean age, 54 years; 34 men) were randomly assigned to aerobic training (n=20), resistance training (n=20), or usual care (n=20). Participants were included if they had a kidney transplant within 12 months prior to baseline assessment. Patients were excluded if they had unstable medical conditions or had recently started regular exercise. Aerobic training and resistance training were delivered 3 days per week for a 12-week period. The usual-care group received standard care. Pulse wave velocity, peak oxygen uptake (Vo2peak), sit-to-stand 60, isometric quadriceps force, and inflammatory biomarkers were assessed at 0 and 12 weeks. The anticipated 60 participants were recruited within 12 months. 46 participants completed the study (aerobic training, n=13; resistance training, n=13; and usual care, n=20), resulting in a 23% attrition rate. Analyses of covariance, adjusted for baseline values, age, and dialysis vintage pretransplantation, revealed significant mean differences between aerobic training and usual care in pulse wave velocity of -2.2±0.4 (95% CI, -3.1 to -1.3) m/s (P<0.001) and between resistance training and usual care of -2.6±0.4 (95% CI, -3.4 to -1.7) m/s (P<0.001) at 12 weeks. Secondary analyses indicated significant improvements in Vo2peak in the aerobic training group and in Vo2peak, sit-to-stand 60, and isometric muscle force in the resistance training group compared with usual care at 12 weeks. There were no reported adverse events, cardiovascular events, or hospitalizations as a result of the intervention. Pilot study, small sample size, no measure of endothelial function. Both aerobic training and resistance training interventions appear to be feasible and clinically beneficial in this patient population.

WS21.2 Skeletal muscle strength measurements in adult CF patients compared to controls

Background In chronic illnesses, such as cystic fibrosis (CF), important muscle weakness has been reported. Aim To study the interaction between handgrip force (HGF), quadriceps force (QF) and six minute walking distance (6MWD) measurements and body composition factors influencing these muscle strengths. Methods A handheld dynamometer was used for HGF, a knee shuttle bank for the isometric QF and a standard 6MWD was performed in CF and controls. Age and body mass index (BMI) were noted for all. Lean body mass %, body fat mass index and fat free mass index (FFMI) of CF patients was assessed by a BIA. Results are median (interquartile range [IQR]). Results 10 age matched controls and 31 CF patients measured muscle strength (Table 1). CF patients display an asymmetric muscle weakness with a relative preservation of the HGF. There was a mutually significant relation of the different strength measurements. All strength measurements were significantly correlated with BMI. Finally, HGF correlated with FFMI (p = 0.011). Table 1ParameterControlsP-valueCF patientsMalesFemalesMalesFemalesAge (yrs)23 (22.3, 25.3)29.5 (22.5, 38.5)n.s.25 (22–31)26 (22.5–33)BMI (kg/m 2 )23.5 (21.3, 24.8)22.5 (21.9, 27.5)0.03120.5 (18.4, 23.3)20.9 (20.1, 21.8)QF (%)103.7 (95.3, 152.2)124.6 (94.8, 156.2)0.000163.5 (52.2, 72.9)55.6 (42.4, 75.8)HGF R (%)164.2 (115.9, 176.6)95.6 (91.4, 108.6)0.000190.9 (72.6, 97.7)87.5 (60.2, 98.5)HGF L (%)183.1 (123.2, 191.8)106.0 (94.7, 119.6)0.000188.1 (73.3, 93.4)83.6 (73.1, 96.8)6MWD (%)84.8 (78.1, 100.1)83.0 (79.0, 88.4)0.000173.2 (63.2, 77.8)72.7 (70.7, 83.4)FFMI17.9 (15.4, 19.1)15.8 (14.4, 16.6)Values are median (IQR). Conclusion Strength parameters are influenced by body composition. Maintaining a healthy BMI is essential in maintaining muscle reserves and as a consequence muscle strength.

Effects of electrical stimulation pattern on quadriceps isometric force and fatigue in individuals with spinal cord injury.

Variable frequency trains (VFT) or train combinations have been suggested as useful strategies to offset the rapid fatigue induced by constant frequency trains (CFT) during electrical stimulation. However, most studies have been of short duration with limited functional application in those with spinal cord injury (SCI). We therefore tested force and fatigue in response to VFT, CFT, and combined patterns in strength training-like conditions (6-s contractions). Ten SCI individuals underwent either CFT or VFT patterns until target torque was no longer produced and then switched immediately to the other pattern. Target torque was reached more times when VFT was used first (VFT: 6.7 ± 0.8 vs. CFT: 3.5 ± 0.2 contractions, P < 0.05) and when it was followed by the CFT pattern (VFT-CFT: 10.3 ± 1.2 vs. 6.9 ± 1.2 contractions, P < 0.05). These findings suggest that for the same initial forces the VFT pattern is less fatiguing than CFT and that when combining train types, VFT should be used first.

Single-dose effects of whole body vibration on quadriceps strength in individuals with motor-incomplete spinal cord injury

ContextParesis associated with motor-incomplete spinal cord injury (SCI) impairs function. Whole body vibration (WBV) may increase strength by activating neuromuscular circuits.ObjectiveWe assessed effects of a single session of WBV on lower extremity strength in individuals with motor-incomplete SCI.DesignA single-session blinded randomized controlled trial.SettingRehabilitation research laboratory.ParticipantsSubjects (n = 25; age 49.7 ± 12.5 years) had chronic SCI (>1 year) and were able to stand for at least 45 seconds.InterventionsSubjects were randomized either to WBV (n = 13) consisting of four 45-second bouts with 1-minute intervening rest periods (frequency: 50 Hz, amplitude: 2 mm) or to sham electrical stimulation (n = 12).Outcome measuresMaximal voluntary isometric quadriceps force was measured with a fixed dynamometer. A modified Five-Time-Sit-To-Stand (FTSTS) test was used to assess functional lower extremity strength. Measures were made at pre-test, immediate post-test, and delayed post-test 20 minutes later.ResultsAt immediate post-test, change in voluntary isometric force in the WBV group was 1.12 kg greater than in the sham group. The within-group change for the WBV group was significant with a moderate effect size (P = 0.05; ES = 0.60). No force-related changes were observed in the sham group. The modified FTSTS scores improved in both groups, suggesting that this measure was subject to practice effects.ConclusionEvidence from the present study suggests that even a single session of WBV is associated with a meaningful short-term increase in quadriceps force-generating capacity in persons with motor-incomplete SCI. The multi-session use of WBV as part of a strengthening program deserves exploration.

Effects of electrical stimulation pattern on quadriceps isometric force and fatigue in individuals with spinal cord injury

Introduction Variable frequency trains (VFT) or train combinations have been suggested as useful strategies to offset the rapid fatigue induced by constant frequency trains (CFT) during electrical stimulation. However, most studies have been of short duration with limited functional application in those with spinal cord injury (SCI). We therefore tested force and fatigue in response to VFT, CFT, and combined patterns in strength training-like conditions (6-s contractions). Methods Ten SCI individuals underwent either CFT or VFT patterns until target torque was no longer produced and then switched immediately to the other pattern. Results Target torque was reached more times when VFT was used first (VFT: 6.7 ± 0.8 vs. CFT: 3.5 ± 0.2 contractions, P < 0.05) and when it was followed by the CFT pattern (VFT-CFT: 10.3 ± 1.2 vs. CFT-VFT: 6.9 ± 1.2 contractions, P < 0.05). Conclusions These findings suggest that for the same initial forces the VFT pattern is less fatiguing than CFT and that when combining train types, VFT should be used first. Muscle Nerve 52: 260–264, 2015

Evaluation of Activity Limitation in Patients With Idiopathic Pulmonary Fibrosis Grouped According to Medical Research Council Dyspnea Grade

ObjectiveTo investigate the relations between Medical Research Council (MRC) dyspnea grade and peripheral muscle force, activities of daily living (ADL) performance, health status, lung function, and exercise capacity in subjects with idiopathic pulmonary fibrosis (IPF). DesignProspective cross-sectional observational study. SettingUniversity hospital. ParticipantsSubjects with IPF (N=65, 46 men) in a stable clinical state with a mean age of 68±7 years. InterventionsNot applicable. Main Outcome MeasuresRight ventricular systolic pressure (RVSP) via transthoracic echocardiography, pulmonary function, isometric quadriceps force (QF) and handgrip force (HF), 6-minute walk distance (6MWD), ADL score, and health status (Medical Outcomes Study 36-Item Short-Form Health Survey [SF-36]) were assessed and compared between subjects grouped according to MRC grade. ResultsOf the participants, 16 were in MRC grade 2, 17 were in MRC grade 3, 17 were in MRC grade 4, and 15 were in MRC grade 5. RVSP, pulmonary function, QF, HF, 6MWD, ADL, and SF-36 scores decreased with increasing MRC grade (all P<.001). All measures were lower (P<.05) in subjects with grades 4 and 5 than subjects with grades 2 and 3. Strong associations were found between MRC grade and 6MWD (ρ=−.89, P=.001) and ADL score (ρ=−.82, P=.001). MRC grade was also associated with RVSP, pulmonary function, QF, and HF (all ρ≥.56, P=.001). ConclusionsThe MRC dyspnea scale provides a simple and useful method of categorizing individuals with IPF with respect to their activity limitation and may assist in understanding the impact of IPF on an individual.

Proprioception in Subjects with Patellofemoral Pain Syndrome: Using the Sense of Force Accuracy

AbstractObjective: Comparison of the ability of reproducing isometric quadriceps force in patients with patellofemoral pain syndrome [PFPS] and healthy normal control subjects.Methods: The Ipsilateral Limb Matching method was utilized to assess the acuity of the sense of isometric force in the quadriceps muscle. At first, participants produced 20 and 60% of quadriceps maximal voluntary isometric contraction using an isokinetic dynamometer and visual feedback, and then they attempted to reproduce the target forces without visual feedback. They were asked to estimate and reproduce the target forces based on their own perception of the quadriceps force used earlier during the isometric contraction with feedback. This test was performed in 20° and 60° of knee flexion. The absolute error, constant error and variable error were used to measure the subjects' errors in their perception of sense of force.Results: Seventeen patients with PFPS [19 to 39 years old] and 17 matched healthy controls participated. The re...

AB0832-HPR Resistance exercise training for women with fibromyalgia

BackgroundStudies show that women with fibromyalgia (FM) are less physically active, have lowered physical capacity and experience limitations in daily activities compared to healthy women. Many patients with FM experience...

The Association Between Submaximal Quadriceps Force Steadiness and the Knee Adduction Moment During Walking in Patients With Knee Osteoarthritis

Cross-sectional study. To investigate the relationship between quadriceps force steadiness and knee adduction moment during walking in patients with knee osteoarthritis (OA). Studies have shown that quadriceps force steadiness is impaired in patients with knee OA. Furthermore, patients with knee OA, compared to healthy controls, have also demonstrated a significantly higher external knee adduction moment during walking. However, no studies have examined the relationship between quadriceps force steadiness and the peak knee adduction moment during walking in this population. Forty-one patients with knee OA (34 females and 7 males) were included in the study. Submaximal isometric quadriceps force steadiness was measured during a force target-tracking task. Peak knee adduction moments during ambulation were measured using a 3-dimensional gait analysis system, and knee pain was assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale and a visual analog scale. Regression analyses showed that quadriceps force steadiness did not predict the peak knee adduction moment (adjusted R2 = 0.05, P = .41). Inclusion of covariates did not change the outcome. No statistically significant association between submaximal isometric quadriceps force steadiness and peak knee external adduction moments during walking was found. It could be speculated that submaximal isometric quadriceps muscle force steadiness and knee joint loads during walking represent 2 distinctive pathways and may have independent influences on knee OA pathogenesis.

Physical Profile Of Flemish Youth And Olympic-class Sailors

PURPOSE: In this study, the physical characteristics of 53 Flemish youth and Olympic-class sailors was related to their class of vessel and their ranking of sailing performance (based on national rankings). METHODS: The anthropometric profile (height, weight, BMI and fat %) of 53 Flemish sailors, including 11 male optimist and 10 male Laser Radial sailors, was determined. They also performed an isokinetic test (Iso) and incremental exercise protocol (IEP). The Iso consisted of 3 exercise protocols: (1) Three alternating 5 s maximal unilateral (Max Un) isometric knee extensions and flexions were performed for both legs, with 90 s recuperation time between each contraction. All contractions were performed at 60° knee flexion and 120° hip angle. (2) Five Max Un concentric knee extension-flexions were performed for both legs at angular velocity (ω) 30°·s-1, over range of motion (ROM) 20° - 70° knee flexion. Hip angle measured 120°. (3) Five Max Un eccentric knee extension-flexions were performed for both legs at ω 30°·s-1, over ROM 20° - 70° knee flexion. Hip angle was again kept at 120°. Two IEP's were used. Athletes < 16 yr performed a ramp IEP and athletes ≥ 16 yr performed a step IEP. Spearman's rho correlation coefficient (CC) and multiple regression were conducted for statistical analysis. RESULTS: The results show for both male optimist and male Laser Radial group a significant correlation between ranking and maximal isometric Quadriceps peak force of the right leg (Isom Q R). CC were respectively -0,664 (p = 0,026) and -0,691 (p = 0,019). Also, for both groups resp. 41,9 % and 56,4 % of the variation in ranking scores was accounted by Isom Q R (equations were resp. Y = 23,918 - 0,105 X and Y = 16,569 - 0,041 X). In addition, mean conventional isometric H/Q-ratio (benchmark = 60 %) and functional H/Q-ratio (benchmark = 100 %) for all sailors were resp. 42,7 ± 7,8 % and 79,0 ± 16,8 %. CONCLUSIONS: This study shows the importance of maximal isometric Quadriceps force concerning sailing performance. However, the Hamstring muscles show a limited capacity for knee joint stabilization, which suggests sailors need to strengthen their Hamstring muscles to prevent the incidence of knee injuries. Supported by the Flemish Government, Ministry of Culture, Youth, Sport and Media. Project title: Olympic Dinghy Sailing 2009-2012

Altered molecular metabolism of knee joint tissues in a botox induced quadriceps muscle weakness model in the rabbit

BackgroundMuscle weakness due to joint injuries (eg, anterior cruciate ligament rupture) or muscle injuries (eg, muscle strain) are very frequent in sports.ObjectiveTo analyze changes to knee joint ligaments and menisci...

Assessing contractile ability of the quadriceps muscle using ultrasound imaging

Muscle dimension changes on ultrasound imaging (USI) indicate contractile activity. Quadriceps force and rectus femoris (RF) dimensions were examined to assess USI for estimating contraction level. In 15 healthy males, mean age 24.8 years, isometric quadriceps force was measured in 90° knee flexion during submaximal and maximal voluntary contractions (MVCs) and at MVC in extension. Mid-thigh cross-sectional area (CSA), depth and width, and surface electromyography (EMG) of RF were recorded. Muscle width decreased curvilinearly as both force and EMG increased. At MVC, width was 3.2 ± 0.5 cm, 25% smaller than at rest (4.4 ± 0.7 cm), and similar to MVC in extension (-23%). CSA decreased linearly to -18% at MVC. RF thickness increased by only 10% (at 30% to MVC). Similar width changes at MVC in flexion and extension indicate the clinical potential of USI for assessing quadriceps contractility. Sensitivity is limited to assessing strength to within 25% of MVC in young males.

Effects of chocolate milk consumption on markers of muscle recovery following soccer training: a randomized cross-over study

BackgroundThe efficacy of chocolate milk (CM) as a recovery beverage following a period of increased training duration (ITD) was studied in intercollegiate soccer players.Methods13 subjects completed one week of normal 'baseline' training followed by four days of ITD. After each day of ITD, subjects received either a high-carbohydrate (504 kcal; CHO: 122 g; 2 g Fat) or isocaloric CM (504 kcal; 84 g CHO; 28 g Pro; 7 g Fat) recovery beverage. Serum creatine kinase (CK), myoglobin (Mb), muscle soreness, fatigue ratings and isometric quadriceps force (MVC) were obtained prior to ITD, and following 2- and 4-days of ITD. Performance tests (T-drill, vertical jump) were performed within training sessions. Treatments were administered in a randomly counterbalanced protocol, and subjects repeated the procedures with the alternate beverage following a two-week washout period.ResultsMean daily training time and HR increased (p < 0.05) between baseline training and ITD, with no differences between treatments. No treatment*time effects were observed for Mb, muscle soreness, fatigue ratings and MVC. However, serum CK was significantly lower (p < 0.05) following four days of ITD with CM (316.9 ± 188.3 U·L-1) compared to CHO (431.6 ± 310.8 U·L-1). No treatment differences were observed for the performance tests.ConclusionsPost-exercise CM provided similar muscle recovery responses to an isocaloric CHO beverage during four-days of ITD. Future studies should investigate if the attenuated CK levels observed with CM have functional significance during more demanding periods of training.

Early exercise in critically ill patients enhances short-term functional recovery*

: To investigate whether a daily exercise session, using a bedside cycle ergometer, is a safe and effective intervention in preventing or attenuating the decrease in functional exercise capacity, functional status, and quadriceps force that is associated with prolonged intensive care unit stay. A prolonged stay in the intensive care unit is associated with muscle dysfunction, which may contribute to an impaired functional status up to 1 yr after hospital discharge. No evidence is available concerning the effectiveness of an early exercise training intervention to prevent these detrimental complications. : Randomized controlled trial. : Medical and surgical intensive care unit at University Hospital Gasthuisberg. : Ninety critically ill patients were included as soon as their cardiorespiratory condition allowed bedside cycling exercise (starting from day 5), given they still had an expected prolonged intensive care unit stay of at least 7 more days. : Both groups received respiratory physiotherapy and a daily standardized passive or active motion session of upper and lower limbs. In addition, the treatment group performed a passive or active exercise training session for 20 mins/day, using a bedside ergometer. : All outcome data are reflective for survivors. Quadriceps force and functional status were assessed at intensive care unit discharge and hospital discharge. Six-minute walking distance was measured at hospital discharge. No adverse events were identified during and immediately after the exercise training. At intensive care unit discharge, quadriceps force and functional status were not different between groups. At hospital discharge, 6-min walking distance, isometric quadriceps force, and the subjective feeling of functional well-being (as measured with "Physical Functioning" item of the Short Form 36 Health Survey questionnaire) were significantly higher in the treatment group (p < .05). : Early exercise training in critically ill intensive care unit survivors enhanced recovery of functional exercise capacity, self-perceived functional status, and muscle force at hospital discharge.

Evidence Of Central And Peripheral Fatigue After A Functional Fatigue Protocol

Muscle fatigue often occurs during athletic participation, and may lead to injury. The mechanisms that produce muscular fatigue during intermittent, multi-directional exercise (e.g., soccer or basketball) remain unknown. We propose that central activation failure (CAF) will account for a major portion of the decrease in muscle force production that occurs during a functional fatigue protocol (FFP) designed to simulate high-level activities. PURPOSE: To determine the extent of central and peripheral fatigue during a FFP in unimpaired individuals. METHODS: Fourteen (7 M, 7 F) recreationally-active participants volunteered for this study (age: 21±2years, height: 175±9cm, mass: 68±8kg). The FFP consisted of a maximum-effort timed 90m agility course and 5 standing broad jumps for maximum distance. The FFP was repeated (with a 5-sec rest between each repetition) until the time to complete the agility course exceeded 150% of the initial repetition. Voluntary (MVC) and electrically-elicited (EEC) peak isometric quadriceps torque, and maximum vertical jump height (VJ), were measured pre- and post-FFP. Central fatigue was assessed by using the twitch superimposition technique to measure CAF in the quadriceps. A 130V, 10 pulse train of electrical impulses (lasting 100ms) were delivered via two electrodes placed over the quadriceps during a 3s MVC. Peak torque was calculated 100ms prior to, and immediately after the initiation of the electrical pulses. CAF was calculated as the change in peak torque (EEC-MVC) divided by the EEC torque. Peripheral fatigue was assessed by examining the change in EEC torque. Paired t-tests and bivariate correlations were performed to analyze the results between conditions. RESULTS: CAF increased post-fatigue (pre:3.5±2.8%; post:10.2±6.2%, p = 0.004). Both MVC (166.4±40.1Nm to 139.1±42.3Nm, p = 0.010) and EEC (172.7±41.8Nm to 153.7±40.7Nm, p = 0.018) decreased post-fatigue. The change in CAF was highly correlated to the loss of MVC torque (r = 0.797), explaining 59.4% of the variance (p = 0.002). VJ also decreased post-fatigue (48.5±8.3cm to 45.4±11.8cm, p = 0.034). CONCLUSION: This FFP produces significant levels of central and peripheral fatigue and decreases isometric quadriceps force and VJ height. The loss of voluntary muscle force is significantly related to the change in CAF.