Maximal Concentric Strength Research Articles

Eccentric Resistance Exercise Effects on Older Adults With Metabolic Syndrome

Background This nonrandomized pilot study explored how whole-body eccentric resistance exercise training (ECC-RT) would change physical fitness and health parameters of older adults with metabolic syndrome symptoms. We hypothesized that ECC-RT would effectively improve neuromuscular and cardio-metabolic parameters. Methods Six men and 11 women aged between 62 and 79 (70.0 ± 5.0) years with body mass index >25 kg · m−2, dyslipidemia, and some indications of metabolic syndrome participated in this study. All performed 8 ECC-RT exercises of the major muscle groups twice a week for 8 weeks with a gradual increase in intensity from 10% to 100% of their maximal concentric strength assessed by 1-repetition maximum (1-RM) for each exercise. Before and after the training intervention, 1-RM strength of all exercises, physical function tests, sensory organization test (SOT) for balance, body composition, and some cardio-metabolic blood markers were measured. Results All participants completed 16 training sessions without any injuries or adverse effects. The concentric 1-RM strength increased (P < 0.05) for all exercises from baseline by 34.1% ± 13.8% (lateral pulldown) to 115.8% ± 108.7% (calf raise). Significant (P < 0.05) improvement of 400-m walk (12.8% ± 6.7%), repeated chair rise (18.6% ± 16.4%), timed up and go (13.6% ± 6.0%), and vestibular (26.1% ± 37.9%) and total score (6.5% ± 8.3%) in SOT were evident, although large variations in responses were observed among participants. However, no significant changes in body composition and blood markers were found. Conclusion The ECC-RT was tolerable for all participants and was effective for improving muscle strength and some physical function tests, but did not affect the metabolic syndrome parameters, possibly because of the short intervention period and small sample size.

The Influence of Eccentric Muscle Actions on Concentric Muscle Strength: An Exception to the Principle of Specificity?

The principle of specificity suggests that the largest changes in strength occur when training resembles the specific strength test. A one-repetition maximum (1RM) test, which tests the maximal concentric strength, is commonly used as a surrogate for strength adaptation. When separating muscle actions into concentric or eccentric phases, multiple lines of evidence suggest that eccentric muscle actions possess several distinct physiological properties compared with concentric actions. In accordance, there are instances where the increases in 1RM strength test were similar between eccentric-only and concentric-only resistance training. This is at odds with the principle of specificity which suggests that individuals who trained with concentric actions would be expected to have an advantage in that specific task. Although the mechanistic reasons why eccentric-biased training carries over to maximal concentric strength remains to be elucidated, the lack of discernible differences in strength gains with eccentrically-biased training (e.g., eccentric-only and accentuated eccentric training) may imply that the effects of eccentric loading in training are transferable to concentric strength. Our review revisits the role of eccentric loading in enhancing concentric maximal muscle strength. We also speculate on potential physiological factors (i.e., molecular and neural factors) that may differentiate the effects of eccentric and concentric resistance training on the changes in muscle strength. Currently, the majority of the studies investigating the changes in strength have been conducted using isokinetic eccentric training. This is important as there is a viewpoint that the magnitude of chronic adaptations with different modalities of eccentric exercises (i.e., isotonic, isokinetic, and isoinertial training) may also differ from each other. While it has been suggested that eccentric action has a greater transferable capacity for strength adaptations compared to concentric actions, future investigations are warranted to investigate with different modalities of eccentric exercises. There also remains a host of unanswered questions related to the role of eccentric action for maximal concentric strength. For example, future studies may examine whether the eccentric action would be additive when the training is already maximally loaded during the concentric action for increasing concentric maximal strength. We suggested a few different designs that could be used to answer some of these questions in future studies.

A Moderate Blood Flow Restriction Pressure Does Not Affect Maximal Strength or Neuromuscular Responses.

Lubiak, SM, Lawson, JE, Gonzalez Rojas, DH, Proppe, CE, Rivera, PM, Hammer, SM, Trevino, MA, Dinyer-McNeely, TK, Montgomery, TR, Olmos, AA, Sears, KN, Bergstrom, HC, Succi, PJ, Keller, JL, and Hill, EC. A moderate blood flow restriction pressure does not affect maximal strength or neuromuscular responses. J Strength Cond Res XX(X): 000-000, 2024-The purpose of this study was to examine the acute effects of blood flow restriction (BFR) applied at 60% of total arterial occlusion pressure (AOP) on maximal strength. Eleven college-aged female subjects completed two testing sessions of maximal unilateral concentric, isometric, and eccentric leg extension muscle actions performed with and without BFR. Separate 3 (mode [isometric, concentric, eccentric]) × 2 (condition [BFR, no BFR]) × 2 (visit [2, 3]) repeated-measures analysis of variances were used to examine mean differences in maximal strength, neuromuscular function, rating of perceived exertion (RPE), and pain. For maximal strength (collapsed across condition and visit), isometric (128.5 ± 22.7 Nm) and eccentric (114.5 ± 35.4 Nm) strength were greater than concentric maximal strength (89.3 ± 22.3 Nm) (p < 0.001-0.041). Muscle excitation relative (%) to isometric non-BFR was greater during the concentric (108.6 ± 31.5%) than during the eccentric (86.7 ± 29.2%) (p = 0.045) assessments but not different than isometric (93.4 ± 17.9%) (p = 0.109) assessments, collapsed across condition and visit. For RPE, there was an interaction such that RPE was greater during non-BFR (4.3 ± 1.7) than during BFR (3.7 ± 1.7) (p = 0.031) during the maximal concentric strength assessments. Furthermore, during maximal strength assessments performed with BFR, isometric RPE (5.8 ± 1.9) was greater than concentric (3.7 ± 1.7) (p = 0.005) and eccentric (4.6 ± 1.9) (p = 0.009) RPE. Finally, pain was greater during the isometric (2.8 ± 2.1 au) than during the concentric (1.8 ± 1.5 au) (p = 0.016), but not eccentric, maximal strength assessments (2.1 ± 1.6 au) (p = 0.126), collapsed across condition and visit. The application of BFR at 60% AOP did not affect concentric, isometric, or eccentric maximal strength or neuromuscular function. Trainers, clinicians, and researchers can prescribe exercise interventions relative to a restricted (when using a moderate AOP) or nonrestricted assessment of maximal strength.

Lower Extremity Asymmetry Values Derived From Multiple Strength Testing Modes Are Associated With Perceived Functional Capabilities Among University Athletes.

Background: Muscle strength asymmetry and athlete introspective measures are associated with musculoskeletal (MSK) sport injury and reinjury. However, the interrelationship between mechanical and subjective measures of concentric and eccentric limb function needs further exploration. This includes investigating if an athlete's perception of their overall MSK function influences limb asymmetry across different testing modalities. Objectives: To (i) explore the interrelationship between mechanical and subjective measures of lower limb function in university athletes and (ii) compare the consistency in interlimb strength asymmetries across different strength tests in groups of athletes with good, fair, and poor perceived limb function. Methods: University athletes (n = 175; n = 87 females) from six sports completed four tests of muscle strength, power, and plyometric function along with an assessment of perceived limb function using the Sport Fitness Index (SFI). Participants were categorized into high (GOODSFI), fair (FAIRSFI), and poor (POORSFI) perceived overall MSK function (perceived function) groups. Strength asymmetry indexes evaluated interlimb differences in concentric and eccentric maximal strength, countermovement jump (CMJ) impulse, unilateral CMJ height, and reactive strength index in unilateral repeat hop testing. Cumulative link mixed-effects models assessed the relationship between strength asymmetries and perceived limb function. Results: The POORSFI group showed increased asymmetry in concentric strength testing (p = 0.022), more consistent interlimb asymmetries (p < 0.001), and reduced overall muscle strength compared to the GOODSFI group. Conclusion: Higher interlimb asymmetry in maximal concentric strength measures along with reduced muscle strength was found in the POORSFI group compared to the GOODSFI group. The POORSFI group also showed greater consistency in muscle strength asymmetry derived across different tasks.

Comparisons of tai chi and Iyengar yoga intervention effects on muscle strength, balance, and confidence in balance.

The aim of the study is to compare a 16-week tai chi and Iyengar yoga program effects on muscle strength, static and dynamic balance, and balance confidence in elderly people. A total of 48 participants (≥60 years old) without mobility-impairing neurological disease, dementia, cardiovascular disease/symptoms during moderate exercise, poorly controlled hypertension, or balance-impairing drug use. Participants were divided into a tai chi group, an Iyengar yoga group, and a control group (eight males and eight females per group), using a restricted randomization scheme generated by software. While the former two undertook 16-week exercise programs, the control group received general education. Maximum concentric strength was measured with an isokinetic dynamometer. The one-legged stand with eyes closed, "8 feet up and go," and Activities-specific Balance Confidence (ABC) scale were used to assess static balance, dynamic balance, and balance confidence in daily activities, respectively. Both programs improved all measures significantly with tai chi being more effective for increasing knee flexor strength (P=0.045) and extensor strength (P=0.032) and ABC score (P=0.034); Iyengar yoga was more effective for improving static balance (P=0.014) and dynamic balance (P=0.025; all P values here vs. the other program). Tai chi and Iyengar yoga can improve strength, balance, and balance confidence among older people. Both are suitable exercise choices for older adults.

Flexor hallucis longus tendon transfer for chronic Achilles tendon rupture. A retrospective study

BackgroundThe transfer of Flexor Hallucis Longus Tendon (FHL) is an established method for the treatment of chronic Achilles tendon ruptures. An extensive examination of power, strength, endurance and complications related to this procedure is presented. Methods21 patients treated with open FHL transfer for chronic Achilles tendon rupture were studied retrospectively. Medical records were reviewed. The patients were examined with a test battery for triceps surae strength, functional tests and PROMs. ResultsThe median maximal concentric strength was equal,1300 vs 1336W, comparing affected with unaffected side. The endurance tests showed a larger difference, 219J vs. 2398J, respectively. The median AOFAS score was 87. 11 of 21 patients sustained one or more complications; the most common were infection, disturbed wound healing, and clawing of small toes. ConclusionsPatients achieve almost normal maximal strength after open FHL transfer, but endurance is notably lower. The complication rate was high.

Supramaximal Eccentrics Versus Traditional Loading in Improving Lower-Body 1RM: A Meta-Analysis

ABSTRACTGuidelines for improving maximal concentric strength through resistance training (RT) have traditionally included large muscle-group exercises, full ranges of motion, and a load approximating 85% of the 1-repetition maximum (1RM). Supramaximal eccentric training (SME; controlled lowering of loads above the concentric 1RM) has also been shown to be effective at increasing concentric 1RM in the lower body, but concerns regarding injury risk, postexercise soreness, and null benefit over traditional methods (TRAD) may limit the practical utility of this approach. Purpose: The purpose of this study was to determine whether SME elicits greater lower-body strength improvements than TRAD. Method: Key inclusion criteria were regular exercise modalities typical of nonspecialized exercise facilities (e.g., leg press; key exclusion: isokinetic dynamometer) and at least 6 weeks of RT exposure, leading to 5 studies included in the current meta-analysis. Unbiased effect-size measures that quantify the mean difference in lower-body 1RM between SME and TRAD were extracted. Results: Supramaximal eccentric training did not appear to be more effective than TRAD at increasing lower-body 1RM ( = .33, SE = .26, z = 1.26, 95% CI [–0.20, 0.79], p = .20, I2 = 56.78%) under a random-effects model where between-study variance was estimated using maximum likelihood estimation ( 2 = .25). Conclusion: The selection of SME over TRAD in RT programs designed to increase lower-body 1RM does not appear warranted in all populations. Further research should clarify the merit of periodic SME in TRAD-dominant RT programs as well as whether a differential effect exists in trained individuals.

Superior Effects of Eccentric to Concentric Knee Extensor Resistance Training on Physical Fitness, Insulin Sensitivity and Lipid Profiles of Elderly Men

It has been reported that eccentric training of knee extensors is effective for improving blood insulin sensitivity and lipid profiles to a greater extent than concentric training in young women. However, it is not known whether this is also the case for elderly individuals. Thus, the present study tested the hypothesis that eccentric training of the knee extensors would improve physical function and health parameters (e.g., blood lipid profiles) of older adults better than concentric training. Healthy elderly men (60–76 years) were assigned to either eccentric training or concentric training group (n = 13/group), and performed 30–60 eccentric or concentric contractions of knee extensors once a week. The intensity was progressively increased over 12 weeks from 10 to 100% of maximal concentric strength for eccentric training and from 50 to 100% for concentric training. Outcome measures were taken before and 4 days after the training period. The results showed that no sings of muscle damage were observed after any sessions. Functional physical fitness (e.g., 30-s chair stand) and maximal concentric contraction strength of the knee extensors increased greater (P ≤ 0.05) after eccentric training than concentric training. Homeostasis model assessment, oral glucose tolerance test and whole blood glycosylated hemoglobin showed improvement of insulin sensitivity only after eccentric training (P ≤ 0.05). Greater (P ≤ 0.05) decreases in fasting triacylglycerols, total, and low-density lipoprotein cholesterols were evident after eccentric training than concentric training, and high-density lipoprotein cholesterols increased only after eccentric training. These results support the hypothesis and suggest that it is better to focus on eccentric contractions in exercise medicine.

Reduced muscular fatigue after a 12-week leucine-rich amino acid supplementation combined with moderate training in elderly: a randomised, placebo-controlled, double-blind trial

BackgroundAge-related muscle loss is characterised by a progressing decrease in muscle mass, strength and function. Besides resistance training and physical activity, appropriate nutrition that is rich in protein, especially branched-chain...

Effects of a systemic enzyme therapy in healthy active adults after exhaustive eccentric exercise: a randomised, two-stage, double-blinded, placebo-controlled trial

BackgroundSystemic enzyme therapy may improve symptoms of exhaustive eccentric exercise due to anti-inflammatory properties.MethodsIn a randomised, placebo-controlled, two-stage clinical trial, systemic enzyme therapy (Wobenzym) was administered for 72 hours before...

Quadriceps And Hamstring Strength

Strength imbalances between the quadriceps and hamstring muscle groups, commonly measured with the hamstring to quadriceps ratio (HQR), are associated with performance decrements and injury risk. Many years of high intensity training completed by collegiate runners may contribute to such imbalances. Early identification of these imbalances may be useful for improving performance and reducing injury risk. PURPOSE:The purpose of this study was to determine if the number of years participating on an intercollegiate cross-country team influences hamstring strength, quadriceps strength, or HQR. METHODS: 10 female intercollegiate cross country runners with varying years of Division-1 experience (3-years, n=4; 2-years, n=3; 1-year, n=3) granted written consent and performed isokinetic testing of the dominant limb to determine maximal concentric strength of the quadriceps and hamstring muscle groups (3 reps; 120°/s; Biodex, Shirley, NY). The maximum torque value of all trials was selected and HQR was calculated for each participant. A linear regression was used to assess how collegiate experience influenced HQR, quadriceps strength and hamstring strength. RESULTS: Strength measures are reported in Table 1. A negative trend (R2=0.998) was observed in HQR. A positive trend (R2=0.747) was observed in quadriceps strength. No trend (R2=0.074) was observed in hamstring strength CONCLUSIONS:The findings suggest that athletes with more years of collegiate cross-country participation have a lower HQR. As there was no trend in hamstring strength, the difference in HQR may be attributed to the trend of greater quadriceps strength in athletes with more years on the team.

Chronic Eccentric Cycling Improves Quadriceps Muscle Structure and Maximum Cycling Power

An interesting finding from eccentric exercise training interventions is the presence of muscle hypertrophy without changes in maximum concentric strength and/or power. The lack of improvements in concentric strength and/or power could be due to long lasting suppressive effects on muscle force production following eccentric training. Thus, improvements in concentric strength and/or power might not be detected until muscle tissue has recovered (e. g., several weeks post-training). We evaluated alterations in muscular structure (rectus-femoris, RF, and vastus lateralis, VL, thickness and pennation angles) and maximum concentric cycling power (Pmax) 1-week following 8-weeks of eccentric cycling training (2×/week; 5-10.5 min; 20-55% of Pmax). Pmax was assessed again at 8-weeks post-training. At 1 week post-training, RF and VL thickness increased by 24±4% and 13±2%, respectively, and RF and VL pennation angles increased by 31±4% and 13±1%, respectively (all P<0.05). Compared to pre-training values, Pmax increased by 5±1% and 9±2% at 1 and 8 weeks post-training, respectively (both P<0.05). These results demonstrate that short-duration high-intensity eccentric cycling can be a time-effective intervention for improving muscular structure and function in the lower body of healthy individuals. The larger Pmax increase detected at 8-weeks post-training implies that sufficient recovery might be necessary to fully detect changes in muscular power after eccentric cycling training.

Prior Eccentric Exercise Reduces V[Combining Dot Above]O2peak and Ventilatory Threshold but Does Not Alter Movement Economy During Cycling Exercise

Exercise-induced muscle damage (EIMD) has been shown to reduce force production and result in delayed-onset soreness and pain in the damaged muscle(s). Cycling in the presence of EIMD reduces peak power output and time-trial performance. However, its effect on peak aerobic capacity has not been widely studied. The purpose of this study was to examine the impact of EIMD targeted specifically to the quadriceps muscle group on peak oxygen consumption (V[Combining Dot Above]O2peak) during cycling. Ten participants (4 men, 6 women) completed a V[Combining Dot Above]O2peak test on a cycle ergometer before and 48 hours after performing 24 eccentric contractions with their right and left quadriceps with a weight equal to 120% of 1-repetition maximal concentric strength (1RM). The EIMD was assessed using 1RM, and muscle soreness was assessed using a 100-mm visual analog scale. The presence of EIMD was confirmed by a 9% reduction in 1RM (p = 0.0001) and increased ratings of soreness from 2.4 ± 2.1 to 24.6 ± 10.8 mm (p = 0.001). The V[Combining Dot Above]O2peak was reduced from 46.2 ± 9.7 to 41.8 ± 10.7 ml·kg·min (10%; p = 0.01) with participants terminating exercise at lower heart rates 191 ± 9 vs. 186 ± 10 b·min (p = 0.02) and power output 248 ± 79 vs. 238 ± 81 W (p = 0.02) after EIMD. Additionally, ventilatory threshold decreased from 34.2 ± 7.8 to 30.5 ± 8.5 ml·kg·min (11%; p = 0.031). Despite the reduction in V[Combining Dot Above]O2peak, cycling economy (p = 0.17) did not differ pre-EIMD and post-EIMD. These findings indicate that EIMD reduced peak aerobic exercise capacity to an extent that could result in meaningful reductions in exercise performance. The reduction is likely attributable to a combination of reduced strength, earlier accumulation of lactic acid, and heightened muscle pain during exercise.

Rate Of Velocity Development Less Decreased Following The Repeated Bout Of Maximal Eccentric Exercise

It has been reported that rate of velocity development (RVD) and strength are two of important measures of athletic performance, and eccentric exercise-induced muscle damage can be impaired RVD and strength performance (Nguyen et al., 2009 JSRC). It is well-documented that a bout of eccentric exercise confers protection against muscle damage after a subsequent bout of the same exercise performed several weeks to several months later (Clarkson et al., 1992 MSSE), but no study has examined effect of repeated bout of eccentric exercise on changes in RVD. PURPOSE: This study was to test the hypothesis that a repeated bout of maximal eccentric exercise of the elbow flexors would be less decreased RVD and faster recovery in comparison with the first bout. METHODS: Ten untrained young men (21.0 ± 3 yrs) performed 2 bouts of 30 maximal eccentric exercises (MAX1 & MAX2; 30°/s) of the elbow flexors of the non-dominant arm separated by 2 weeks. Maximal isokinetic concentric strength (MVC) and RVD (300°/s), muscle soreness, and range of motion were measured before, immediately after, and for 5 consecutive days after each bout. All data was analyzed by a two-way repeated measures ANOVA. RESULTS: The first bout of maximal eccentric exercise produced significant (P<0.05) decrease in maximal concentric strength (39%), RVD (49%), range of motion, and increase in muscle soreness. The changes in all criterion measures (e.g. MVC: 30%, RVD: 44%) after the second bout of the same exercise were significantly smaller (P<0.05) than that of the first bout. CONCLUSION: These results supported that MAX1 induced significantly muscle damage and soreness would be affected RVD, and protective effect occurred following the first bout of eccentric exercise results in a smaller decrease in RVD and faster recovery when the exercise is repeated after 2 weeks.

Effects of Different Accentuated Eccentric Load Levels in Eccentric-Concentric Actions on Acute Neuromuscular, Maximal Force, and Power Responses

This study examined the effects of different dynamic accentuated external resistance load levels during the eccentric(ECC) phase of ECC-concentric (CON) actions on acute neuromuscular, maximal force, and power responses in the bench press exercise in male subjects (age, = 32 +/- 4 years; n = 11). Four maximum strength sessions consisted of 1 repetition maximum (RM) lifts with traditional isoinertial resistances and of 1RM lifts with the different dynamic accentuated external resistance (DAER) loads of 100, 105, 110, and 120% of 1 RM for the ECC phase, whereas 100% of 1RM was constantly used for the CON phase. One explosive strength session consisted of explosive repetitions with the 50, 60, 70, 80, and 90% of 1RM loads for the ECC phase, whereas 50% of 1RM was constantly used for the CON phase. Force, power, and electromyography (EMG) activation of agonist deltoid, pectoralis major, triceps brachii, and antagonist biceps brachii muscles were recorded. In all maximum strength DAER sessions (105/100%, 110/100%, and 120/100%), CON 1RM and CON force reduced (p < 0.05) compared with the control condition (100/100%). ECC muscle activity did not differ in the DAER loading conditions compared with the control loading condition. In the explosive strength session, peak power increased significantly from the 50/50% condition compared to the condition of 77.3 +/- 3.2/50% (p < 0.001) that produced the highest power for each individual. ECC agonist EMG activity increased significantly from the 50% condition to that of the 77.3 +/- 3.2/50% condition (p < 0.05). The present data showed that the different loads used in the DAER bench press action did not enhance maximum concentric strength production, but concentric power output during explosive actions with the individualized optimal load was larger compared with the control condition.

Changes in muscle strength, endurance, and reaction of the lower extremities with Tai Chi intervention

This study examines the effects of a 16-week Tai Chi (TC) training program on the muscle strength, endurance, and reaction time of the lower extremities of elderly people. A total of 40 elderly individuals (aged ⩾60 years) completed the study. They were divided into two groups: the TC group (11 men and 11 women) underwent a supervised TC exercise program for 16 weeks, while the control group (9 men and 9 women) received general education for a comparable time period. Pre- and post-intervention measurements were conducted. An isokinetic dynamometer was used to measure the maximum concentric strength and dynamic endurance of the knee flexors and the extensors, and the maximum concentric strength of the ankle plantarflexors and dorsiflexors. The neuromuscular response of the rectus femoris, semitendinosus, gastrocnemius, and anterior tibialis muscles was measured by the onset latency to sudden perturbations using an electromyography system. After 16 weeks, the TC group showed a 19.9% increase in muscle strength of the knee flexors ( p<.000) that was significantly greater than that in the control group ( p=.046). There was also a significant decrease in semitendinosus muscle latency (6.6%, p=.014) that was significantly shorter than that in the control group ( p=.042). No significant training effects were found in other measures. These results suggest that improving biomechanical characteristics of lower extremity muscles may need longer TC intervention for elderly people.

Maximal eccentric and concentric strength discrepancies between young men and women for dynamic resistance exercise.

Although research has demonstrated that isokinetic eccentric (ECC) strength is 20-60% greater than isokinetic concentric (CON) strength, few data exist comparing these strength differences in standard dynamic resistance exercises. The purpose of the study was to determine the difference in maximal dynamic ECC and CON strength for 6 different resistance exercises in young men and women. Ten healthy young men (mean +/- SE, 25.30 +/- 1.34 years), and 10 healthy young women (mean +/- SE, 23.40 +/- 1.37 years) who were regular exercisers with resistance training experience participated in the study. Two sessions were performed to determine CON and ECC 1 repetitions maximum for latissimus pull-down (LTP), leg press (LP), bench press (BP), leg extension (LE), seated military press (MP), and leg curl (LC) exercises. Maximal ECC and maximal CON strength were determined on weight stack machines modified to isolate ECC and CON contractions using steel bars and pulleys such that only 1 type of contraction was performed. Within 2 weeks, participants returned and completed a retest trial in a counterbalanced fashioned. Test-retest reliability was excellent (r = 0.99) for all resistance exercise trials. Men demonstrated 20-60% greater ECC than CON strength (LTP = 32%, LP = 44%, BP = 40%, LE = 35%, MP = 49%, LC = 27%). Women's strength exceeded the proposed parameters for greater ECC strength in 4 exercises, p < 0.05 (LP = 66%, BP = 146%, MP = 161%, LC = 82%). The ECC/CON assessment could help coaches capitalize on muscle strength differences in young men and women during training to aid in program design and injury prevention and to enhance strength development.

Effects of long term Tai Chi practice and jogging exercise on muscle strength and endurance in older people

Objectives: To investigate the influence of regular Tai Chi (TC) practice and jogging on muscle strength and endurance in the lower extremities of older people. Methods: Twenty one long term...

Perceived exertion responses to novel elbow flexor eccentric action in women and men.

The primary aim was to describe perceived exertion responses to different intensities of eccentric exercise in women and men. 42 adults (21 men and 21 women, 7 per condition) completed elbow extension exercises with a weight corresponding to 80%, 100%, or 120% of maximal voluntary concentric strength. Total work was equated by manipulating the number of repetitions in the 80% (N = 45), 100% (N = 36), and 120% (N = 30) conditions. A two-way ANOVA showed significant main effects for the intensity and sex factors. Perceived exertion ratings were strongly dependent on exercise intensity, and women reported lower RPEs than men. A separate three-way mixed model ANOVA that included a repetition factor showed that perceived exertion ratings increased similarly across the first 30 repetitions in all exercise conditions. Significant partial correlations were found between mean RPE during the eccentric exercise bout, and the mean intensity of delayed-onset muscle pain measured from 12- to 72-h postexercise after controlling for the relative exercise intensity (r12.3 = 0.28) or the maximum concentric strength of the elbow flexors (r12.3 = 0.33). 1) for both women and men, there is a positive association between the intensity of eccentric exercise performed with the elbow flexors and RPE; 2) perceived exertion ratings increase significantly then plateau when repeated eccentric muscle actions are performed at constant, submaximal absolute intensities; 3) women rate eccentric exercise performed at the same intensity (relativized to MVC-C) as being less effortful compared with men; and 4) RPE during eccentric exercise can account for a small but significant amount of variability in delayed-onset muscle pain after statistically controlling for differences in strength or relative intensity.

Pulley system isokinetic training in knee rehabilitation--initial results

The purpose of this study was to evaluate the results of a knee rehabilitation program after knee surgery, based on an isokinetic pulley System (Moflex, Recotec/Bernina, Switzerland). In this prospective study, 73 patients participated in a standardized rehabilitation program (ACL reconstruction, ACL/all: n = ;51; patellar tendon, ACL/P: n = 30; semitendinosus tendon, ACL/S: n = 21; arthroscopic meniscus resection: n = 22). The major aspect of the program was an isokinetic pulley system with an implemented, linearly working knee device. Isokinetic training with the used device affords strict monitor feed-back to avoid critical torque values. Concentric training strength and workload which were attained without relevant pain were increased by about 130% within a mean of 16 rehabilitation days. At the end of the rehabilitation program, the maximum concentric strength of the affected knee measured by a rotating isokinetic system (Cybex, Kaphingst, Lahntal) increased by about 69% and amounted to about 90% of that of the unaffected knee. These first results demonstrate the value of the isokinetic pulley system in the rehabilitation after knee surgery as described above. The equipment may be used already in an early postoperative stage by the use of a passive or active-assistive mode. First results of strength increases using an isokinetic pulley system in knee rehabilitation are presented.