Submaximal Repetitions Research Articles

On the Relationship Between Discrete and Repetitive Lifting Performance in Military Tasks

Military manual handling requirements range from discrete lifts to continuous and repetitive lifting tasks. For the military to introduce a discrete lifting assessment, the assessment must be predictive of the various submaximum lifting tasks personnel are required to perform. This study investigated the relationship between discrete and repetitive military lifting to assess the validity of implementing a discrete lifting test. Twenty-one soldiers from the Australian Army completed a whole-body box-lifting assessment as a one repetition maximum (1RM) and a series of submaximal lifting repetitions (% 1RM). Performance was measured between the number of lifting repetitions that could be performed at different intensities between 58 and 95% 1RM. A strong curvilinear relationship existed across the entire submaximal lifting range (r = 0.72, p ≤ 0.05). The model developed demonstrated a low predictive error (standard error of the estimate = 7.2% 1RM) with no differences detected in the relationship when comparing individuals of high and low strength. Findings support the use of a discrete functional lifting assessment in providing coverage of a broad range of military lifting tasks. Parallels can be drawn between the trend reported in the current study and weight-training exercises reported in the literature.

The effects of motor learning on clinical isokinetic performance of postmenopausal women

ObjectiveTo analyze the effects of motor learning on knee extension–flexion isokinetic performance during clinical isokinetic evaluation of postmenopausal women. MethodsOne-hundred and twenty postmenopausal women (60.3±3.2 years; BMI=27.6±4.7kg/m2) without knee pain or injury and that never underwent isokinetic testing, were submitted to two bilateral knee extension–flexion (concentric–concentric) isokinetic evaluation (5 repetitions) at 60°/s (Biodex™ Multi-Joint System 3 dynamometer). The tests were first performed in the dominant leg, with a 1-min recovery between them, and after a standardized warm-up that included 3 submaximal isokinetic repetitions. The same procedure was repeated in the non-dominant leg. Peak torque (PTQ) was adjusted for body weight (PTQ/BW), total work (TW), coefficient of variation (CV) and agonist/antagonist (agon/antag) ratio was compared between tests. ResultsSubjects showed greater levels (P<0.001) of PTQ, PTQ/BW and TW, and lower CV levels (P<0.01) in test 2 of both legs. Agon/antag ratio did not change significantly between tests. ConclusionsPTQ, PTQ/BW, TW and CV improved in the second knee extension flexion isokinetic testing of postmenopausal women. The results suggests that performing two tests, even with a short period of recovery between them, could be considered for reducing motor learning effects on clinical isokinetic evaluation of knee joint in postmenopausal women.

Isokinetic Strength Profiles Among 1st and 2nd division Elite Soccer Players and Young Soccer Players

Isokinetic assessment allows muscle strength and both flexors/extensors and dominant/non-dominant imbalances evaluation. When comparing isokinetic knee strength among different soccer age groups or categories there is some controversy regarding which muscular parameters determine differences between them. PURPOSE:To compare the isokinetic strength profile of knee flexors and extensors among different soccer categories. METHODS:175 soccer players (1st division (n=47), 2nd division (n=23), 15-17 yrs (n=64), and 13-14 yrs (n=41)) (body mass (kg): 78.1 ± 6.9; 72.4 ± 4.9; 71.4 ± 5.6; 64.1 ± 7.9, respectively) from one of the top Spanish Soccer Clubs performed an isokinetic knee test on a Biodex III® dynamometer (Biodex Medical Systems, Shirley, NY). Position was standardized with coxo-femoral joint at 105 deg·sec-1 and knee joint at 100 deg·sec-1 of flexion. Gravitational factor from both lower limb and dynamometer arm were compensated. After a warm up protocol (5 submaximal repetitions at 120 deg·sec-1), players carried out 3 reps at 60 deg·sec-1 in concentric mode of Hamstring (H) and Quadriceps (Q), followed by 3 reps at 60 deg·sec-1 in eccentric mode of H. Peak Torque was expressed in absolute (N·m-1) and relative (N·m-1·kg-1) terms, and different ratios (HCON/QCON and Dynamic Control ratio (DCR)) were compared among groups using a one-way ANOVA for parametric data, and Fisher and Kruskal-Wallis tests for non-parametric data. Statistical significance was set at p <. 05. RESULTS:See Table. CONCLUSIONS:While peak torque values, expressed in N·m-1 and N·m-1·kg-1, increased with category up to the 1st division players, no differences were found for HCON/QCON and DCR ratios among different groups.Table

Strength Imbalance Incidence in Professional Soccer Players According to a Three-Category Classification

There seems to be no general consensus related with the most important isokinetic predictors for injury prevention. Low values of both concentric (HCON/QCON) and Dynamic Control (DCR) ratios have been related with higher injury risk, however it is not clear if dominant/non-dominant imbalances for flexors and extensors are related with injuries. PURPOSE: To study the imbalance incidence in professional soccer players through five consecutive seasons. METHODS: 177 professional soccer players belonging to the 1st and 2nd teams of one of the top Spanish Soccer Clubs, performed an Isokinetic test (Biodex II® or III® dynamometer, Biodex Medical Systems, Shirley, NY) during the first part of five consecutive seasons (04-05 n=25, 05-06 n=46, 06-07 n=38, 07-08 n=23, 08-09 n=45). Position was standardized with coxo-femoral joint at 105 deg·sec-1 and knee joint at 100 deg·sec-1 of flexion. Gravitational factor from both lower limb and dynamometer arm were compensated. After a warm up protocol (5 submaximal repetitions at 120 deg·sec-1), players carried out 3 reps at 60 deg·sec-1 in concentric mode of Hamstring (H) and Quadriceps (Q), followed by 3 reps at 60 deg·sec-1 in eccentric mode of H. The mean and 1 SD of each variable were used to set the limits of the three categories of imbalance: low (LI) if 17%, for dominant/non-dominant imbalance; LI >55, MI 55-47, and HI <47 for HCON/QCON; and LI >72, MI 72-60, and HI <60 for DCR. A Chi-square was used to analyze the frequency distribution in each category of imbalance, along the five seasons. Statistical significance was set at p<0.05. RESULTS: The number of players in the LI range increased for both DCR (Chi-square=27.6, p<0.001) and HCON/QCON (Chi-square=18.7, p<0.05) of the left knee, along the five seasons. No changes were found for the rest of the analyzed variables. CONCLUSIONS: This proposed three-category classification is a useful tool for imbalance detection in professional soccer players.

The effects of stretching on knee flexor fatigue and perceived exertion

The objective of this study was to examine the effects of acute static muscle stretch on hamstring muscle fatigue and perceived exertion between young adult men and women. Twenty volunteers participated in two experimental sessions, in which we assessed maximal-effort isokinetic knee flexor force (90° · s−1) and the number of sub-maximal (50% maximal) knee flexor repetitions to the point of failure. Immediately before the sub-maximal contractions on one randomly selected session, participants received ten 30-s passive knee flexor muscle stretches. Perceived exertion was sampled with a modified Borg category-ratio scale following each sub-maximal repetition. Each participant's perceived exertion response was estimated every 10% across the sub-maximal repetitions, via linear interpolation and power-function modelling. The men generated significantly greater force than the women during both experimental sessions, while muscle stretching had no significant effect on the number of sub-maximal repetitions. When estimated via power-function modelling, perceived exertion increased at a significantly greater rate following muscle stretch. Perceived exertion was significantly greater for the women following muscle stretch than the men. The findings suggest that the elevation in perceived exertion following knee flexor muscle stretching may be greater in women than men, despite no significant alterations in mechanical measures of muscle fatigue.

Superficial Moist Heat’s Lack of Influence on Soleus Function

It is reported that thermotherapy decreases motoneuron-pool recruitment. Any decrease in recruitment might have a significant impact on an athlete's ability to return to competition. To determine whether moist heat application influences involuntary motoneuron-pool recruitment or voluntary plantar-flexion peak torque of the soleus muscle immediately or 30 min after application. A 3 x 3 crossover design. Biomechanics laboratory. Eighteen healthy subjects with no history of lower extremity surgery or injury 12 months before the study volunteered. A series of short-duration, high-intensity stimuli was delivered to the tibial nerve to find the H(max) and M(max) measures. Immediately after the H(max) and M(max) measures, subjects were positioned on an isokinetic dynamometer where they performed 5 submaximal warm-up repetitions. Immediately after the warm-up, 5 maximum-intensity peak plantar-flexion torque repetitions were performed. After the dynamometer measures, subjects returned to the table, where a moist heat pack, no heat pack, or a dry nonheated heat pack was applied. H(max), M(max), peak plantar-flexion torque, surface temperature (degrees C), and ambient temperature (degrees C). Moist heat did not influence the H:M(max) ratio or peak plantar-flexion torque. Temperature increased with moist heat pack. Ambient temperature remained constant. Moist heat did not influence involuntary motoneuron-pool recruitment or voluntary peak plantar-flexion torque of the soleus muscle immediately or 30 min after application.

Predicting One Repetition Maximum Equations Accuracy in Paralympic Rowers with Motor Disabilities

Predicting one repetition maximum equations accuracy in paralympic rowers Resistance training intensity is prescribed using percentiles of the maximum strength, defined as the maximum tension generated for a muscle or muscular group. This value is found through the application of the one maximal repetition (1RM) test. One maximal repetition test demands time and still is not appropriate for some populations because of the risk it offers. In recent years, the prediction of maximal strength, through predicting equations, has been used to prevent the inconveniences of the 1RM test. The purpose of this study was to verify the accuracy of 12 1RM predicting equations for disabled rowers. Nine male paralympic rowers (7 one-leg amputated rowers and 2 cerebral paralyzed rowers; age, 30 +/- 7.9 years; height, 175.1 +/- 5.9 cm; weight, 69 +/- 13.6 kg) performed 1RM test for lying T-bar row and flat barbell bench press exercises to determine upper-body strength and leg press exercise to determine lower-body strength. One maximal repetition test was performed, and based on submaximal repetitions loads, several linear and exponential equations models were tested with regard of their accuracy. We did not find statistical differences for lying T-bar row and bench press exercises between measured and predicted 1RM values (p = 0.84 and 0.23 for lying T-bar row and flat barbell bench press, respectively); however, leg press exercise reached a high significant difference between measured and predicted values (p < 0.01). In conclusion, rowers with motor disabilities tolerate 1RM testing procedures, and predicting 1RM equations are accurate for bench press and lying T-bar row, but not for leg press, in this kind of athlete.

Isokinetic Thigh Muscle Ratios in Youth Football: Effect of Age and Dominance

This study aimed to analyse the effect of age on muscle peak torque (PT), and Hamstring (H): Quadricep (Q) ratio in elite youth footballers. To date, no study has considered age-group playing level and pubertal development in this population. One hundred and fifty-seven elite youth footballers in the age groups U12 to U18 volunteered to participate in this study, 133 of these were further grouped for pubertal development. Prior to testing subjects completed separate familiarisation, a three minute cycle ergometer warm up (resistance 50-60W), and two sub-maximal repetitions. Concentric and eccentric isokinetic PT measures for reps 2-4 of H and Q muscle action were taken at 60 degrees s (-1). From this, conventional and functional H: Q ratio was calculated along with dominant: non dominant ratio for the concentric Q and H, and eccentric H conditions. Significant main effects were observed for the age/pubertal development group and PT in all muscles and conditions (P<0.05). Of particular interest was a significant main effect for age and Functional H: Q (P<0.05), which suggested a move away from equality at U18. Our study provides normative data for coaches, trainers and clinicians working with youth footballers and may also have connotations for injury prevention and performance.

Contraction mode shift in quadriceps femoris muscle activation during dynamic knee extensor exercise with increasing loads

The objective of the present study was to examine the superficial quadriceps femoris (QF) muscle electromyogram (EMG) during dynamic sub-maximal knee extension exercise between young adult men and women. Thirty subjects completed, in a random order, 2 sub-maximal repetitions of single-leg knee extensions at 20–90% of their one-repetition maximum (1RM). Vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscle integrated EMG (IEMG) during each sub-maximal lift was normalized to the respective 1RM for concentric, isometric and eccentric modes. The EMG median frequency ( f med) was determined over the isometric mode. Men attained a significantly ( p<0.05) greater knee angular velocity than the women during the concentric mode (83.6±19.1°/s and 67.4±19.8°/s, respectively). RF IEMG was significantly lesser than the VM ( p=0.014) and VL ( p<0.001) muscles, when collapsed across all contraction modes, loads, and sex. Overall IEMG was significantly greater during the concentric ( p<0.001) and isometric ( p<0.001) modes, than the eccentric mode. Men generated significantly ( p=0.03) greater VL muscle IEMG than the women, while the opposite pattern emerged for the RF muscle. VM f med (105.1±11.1 Hz) was significantly lesser than the VL (180.3±19.5 Hz) and RF (127.7±13.9 Hz) muscles across all lifting intensities, while the men (137.7±10.7 Hz) generated greater values than the women (129.0±11.4 Hz). The findings demonstrate a reduction in QF muscle activation across the concentric to eccentric transition, which may be related to the mode-specific velocity pattern.

Resistance Training for Medial Compartment Knee Osteoarthritis and Malalignment

1) To evaluate the effects of a 12-wk high-intensity knee extensor and flexor resistance training program on strength, pain, and adherence in patients with advanced knee osteoarthritis and varus malalignment and 2) to generate pilot data for change in dynamic knee joint load, patent-reported outcomes, and self-efficacy after training. Fourteen patients (48.35 +/- 6.51 yr) with radiographically confirmed medial compartment knee osteoarthritis and varus malalignment of the lower limb were recruited from a surgical waiting list for high tibial osteotomy. Participants completed a high-intensity isokinetic resistance training program three times per week for 12 wk. Knee extensor and flexor strength were assessed every third week, whereas pain and adherence were recorded at every training session. The external knee adduction moment during the gait, the 6-min-walk test, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Arthritis Self-Efficacy Scale (ASES) were also evaluated before and after training. Significant improvements in knee extensor and flexor strength were observed without increases in pain during or after training. Adherence to the high-intensity program was high. No significant changes were observed for dynamic knee joint load or the KOOS. There was a significant increase in the function subscale of the ASES only. These findings suggest that patients with advanced knee osteoarthritis and malalignment can experience substantial gains in strength after a high-intensity resistance training program without concomitant increases in pain, adverse events, or compromised adherence. These findings provide support for future clinical trials with longer-term outcomes.

Validity of Predicting One Repetition Maximum Strength from Sub-maximal Repetitions to Fatigue

Validity of Predicting One Repetition Maximum Strength from Sub-maximal Repetitions to Fatigue

Predicting Maximal Strength in Trained Postmenopausal Woman

The purpose of this study was to present an equation that accurately predicts 1 repetition maximum (RM) over a wide range of repetitions to fatigue (RTF) for 4 different machine resistance exercises in postmenopausal women. Seventy trained women (age = 57.4 +/- 3.1 years) performed maximal and submaximal repetitions on leg press, bench press, rowing, and leg adduction machines at the conclusion of a 2-year training program. Maximal repetitions were performed on each exercise in the following ranges: 3-5RM, 6-10RM, 11-15RM, and 16-20RM. Special regard was taken to maintain the identical execution of each test (i.e., range of motion, starting angle, speed of movement). One cubic polynomial (w(i) [0.988-0.0000584 r(i)(3) + 0.00190 r(i)(2) + 0.0104 r(i),] where w(i) is the load of measurement I, and r(i) is the number of repetitions) accurately predicted 1RM from RTF with mean absolute differences between actual 1RM and predicted 1RM for the 4 exercises of 1.5-3.1% and with coefficients of variation of <3.3%. Equation accuracy was independent of the exercise type or the number of RTF. Thus, this study supported the validity of RTF to adequately estimate 1RM over a wide range of repetitions and within different exercises in trained, older female subjects.

Isokinetic assessment of the flexor-extensor balance of the knee in athletes with total rupture of the anterior cruciate ligament.

The purpose of this study was to assess the flexor-extensor group of muscles of the knee in young athletes diagnosed with a total rupture of the anterior cruciate ligament (ACL). Eighteen knees of 18 athletes (14 men and 4 women) with an average age of 21.6 years (range 16-32 years) were assessed with a Cybex 6000 model isokinetic apparatus. The average internal between occurrence of the injury and assessment was 10.2 months (range 2-48 months). There was an associated meniscal injury in eight of the knees. Athletes with any other kind of associated injury, limitation, or blockage of the movement of the joint, significant pain during the exam, or interval between injury and exam of less than two months were excluded from the study. The parameters studied were the peak torque-velocity and flexor-extensor relationships at the constant angular velocities of 60 degrees/sec and 240 degrees/sec. Previous warming-up was done by means of an ergometric bicycle and adaptation with 3 submaximal repetitions. The contra-lateral side, which presented no injury, was used as control. Peak torque (PT) at the constant velocity of 60 degrees/sec was greater than that at 240 degrees/sec for knees with and without injuries. However, there was no significant difference between the injured and uninjured sides at 60 degrees/sec or at 240 degrees/sec. The average value for the flexor-extensor relationship at 60 degrees/sec on the injured was 60% ((6), compared to 57% ((10) on the contra-lateral side. At 240 degrees/sec, the average value was 75% ((10) on the injured side, and 65% ((12) on the contra-lateral side. In conclusion, despite the complete rupture of the ACL of one knee, the average values for the flexor-extensor relationship were similar on the injured and uninjured sides at the velocity of 60 degrees/sec. As the velocity increased, an increase in the values for the flexor-extensor relationship of the knee also occurred, indicating a tendency of the performance of the flexor muscle group to approach that of the extensor muscle group, and this tendency was more pronounced on the side of the injury.

Reliability of peak torque values for concentric and eccentric shoulder internal and external rotation on the biodex, kinetic communicator, and lido dynamometers

The purpose of this study was to investigate the concentric and eccentric peak torque reliability of the Biodex B-2000, Kinetic Communicator, and Lido isokinetic dynamometers when testing the shoulder internal and external rotators. The subjects were 22 males with no previous shoulder pathology. Each subject completed two test sessions for each isokinetic dynamometer. The right upper extremity was tested at 1200 /s through a 1400 arc of motion with the shoulder in 900 of abduction. After a warm-up of three sub-maximal repetitions and 1 maximal repetition, five maximal repetitions were completed in either the concentric or eccentric mode. A 5-min rest period lapsed and then the second test mode was completed. Six days later, the subjects were tested in the reverse order. This procedure was completed for each isokinetic dynamometer. Four one-way analyses of variance with repeated measures were used to compare peak torque values of shoulder internal and external rotation in each test mode. The F-values indicated significant differences in concentric and eccentric internal rotation and eccentric external rotation. Therefore indicating that comparisons of peak torque values should not be made between different isokinetic dynamometers. Means, standard error of measurement (SEM), and intraclass correlations (ICC) were calculated for each dynamometer in each test mode. The ICCs for concentric peak torque were generally higher than those of eccentric peak torque, but lower than those reported by previous researchers. Of the many variables that can impact isokinetic testing, position may have been the most influential in this study. It is possible that impingement of the shoulder rotators occured with the shoulder in 90 of abduction. Perhaps another test position would have yielded more consistent results. The presence of delayed onset muscle soreness may have also influenced this study. Copyright © 1996 Elsevier Science Ireland Ltd.

Use of Submaximal Repetition Tests for Predicting 1-RM Strength in Class Athletes

Use of Submaximal Repetition Tests for Predicting 1-RM Strength in Class Athletes

Use of Submaximal Repetition Tests for Predicting 1-RM Strength in Class Athletes

ABSTRACT Twenty-three male college athletes performed submaximal repetition tests (70, 75, 80, 85, 90, and 95% 1-RM) in the bench press (BP), squat (S), and power clean (PC) lifts. For each lift the best predictor of 1-RM strength was defined as the maximal number of repetitions performed at a given lifting intensity (i.e., %1-RM) which represented the highest prediction coefficient (multiple R). ANOVA revealed that regardless of lift, the number of repetitions significantly decreased (p 0.05).

Prediction of bench press lifting ability from submaximal repetitions before and after training

The purpose of this study was to determine the accuracy of predicting maximal bench press lifting strength from submaximal bench press repetitions before and after a training program. College students (70 men; 101 women) were tested to determine their one repetition maximum (1‐RM) bench press lifting strength before and after 14 weeks of training. Several days after an initial maximum lift determination, each subject was randomly assigned a submaximal load corresponding to 55 to 95% of the 1‐RM and required to perform as many bench press repetitions as possible in 1 minute. The same percent 1‐RM was used following training, as was used before training, to test lifting capacity at a defined percent of the initial 1‐RM for a given individual. Men had a significantly greater 1‐RM bench press strength and absolute integrated submaximal weightlifting ability than women but were not significantly different in percent 1‐RM and repetitions. The exponential relationship between percent 1‐RM and repetitions before ...

Isokinetic Lifting Simulation: A Normative Data Study

This article describes a system for data collection using an isokinetic lifting task simulation device and reports normative data findings based on a standardized lifting posture. The test population included 2688 normal subjects (1236 females, 1452 males; ages 10-79 years) from five different occupational categories who were tested on a Liftask device using a flexed knees-flexed back lifting posture. Testing consisted of four maximal lifting repetitions preceded by three gradient submaximal repetitions plus one maximal effort at the speeds of 6, 12, 18, 24, 30, and 36 inches/sec. Data on peak force, peak force as percent of body weight, height of peak force, average force, average force as percent of body weight, average power, and total work were categorized by sex and age decade for reporting as normative experimental results. In general, overall performance decreased in an inverse proportion to test speed while height of peak force and average power increased in direct proportion to speed. Also, subject performance increased from the 10-19 decade to the 20-29 decade before decreasing with age through the 70-79 decade. The results may be useful for clinical reference purposes as normative data for the purposes of performance comparisons during isokinetic lifting with a flexed knee-flexed back posture.J Orthop Sports Phys Ther 1988;10(5):156-166.

Investigation of the Physiological Overflow Effect from Speed-Specific Isokinetic Activity

This article investigates the concept of physiological overflow during speed-specific isokinetic exercise. The idea was tested on 30 volunteers; 14 female, 16 male; mean age 24.5 years, age range 17-29 years; who were subjected to a repeated m o r e s experimental design. Testing involved 5 repetitions of knee extension/flexion at the velocity spectrum speeds of 80, 7 20, 180,240, and 300 degrees /sec preceded by a warm-up at 3 gradient submaximal repetitions and 1 maximal effort at each speed. The experimental treatment consisted of isokinetic exercise of the knee musculature to the level of 50% quadriceps fatigue at the speed of 180 degrees /sec in a format of 3sessions per week over a period of 8 weeks. Analysis of variance testing with repeated measures revealed statistically significant differences in quadriceps and hamstrings function for peak torque, torque acceleration energy, and watts average power at all velocity spectrum speeds over the period of experimentation. It was concluded that a +/-120 degrees /sec physiological overflow of exercise effects to both slower and faster speeds existed during the program of isokinetic activity. J Orthop Sports Phys Ther 1987;9(3):106-110.