Speed Matters in Nordic Hamstring Exercise: Higher Peak Knee Flexor Force during Fast Stretch-Shortening Variant Compared to Standard Slow Eccentric Execution in Elite Athletes.

Hamstring strain injuries are prevalent in many sports. Research has demonstrated that the Nordic hamstring exercise (NHE), a knee-dominant exercise addressing the posterior chain muscles, can aid in reducing the risk of hamstring injuries in athletes. However, most research on hamstring injury prevention has focused on performing the eccentric version of the NHE (NHEECC). In contrast, in sports, it is quite frequent for athletes to use an eccentric-concentric version of the NHE. Additionally, eccentric NHE is typically performed using a slow, controlled tempo. The effect of a fast stretch-shortening cycle NHE (NHESSC) compared to standard slow NHEECC on peak knee flexor force has not been investigated. The aim of the study was therefore to investigate fast NHESSC vs. standard slow NHEECC. Our hypothesis posited that peak knee flexor force would be greater for fast NHESSC compared with standard slow NHEECC. The study involved 22 elite athletes (actively competing in both national and international events) consisting of female (n = 10) and male (n = 7) track and field athletes and male football players (n = 5), aged 17-31 years. The participants performed maximum trials of slow NHEECC and fast NHESSC repetitions in which measurement of bilateral peak knee flexor force was conducted at the ankle with the use of a load cell. During the NHEs, a linear encoder was used to measure both the position where the peak knee flexor force was recorded and the average eccentric velocity. SSC contributed to an enhanced NHE performance, where bilateral absolute peak knee flexor force was 13% higher for fast NHESSC vs. standard slow NHEECC (822 vs. 726 N, p < 0.01, ES = 0.54). Participants achieved a 32% greater forward distance at the breakpoint stage during NHEECC compared to the coupling phase for NHESSC (54 vs. 41 cm, p < 0.001, ES = 1.37). Eccentric average velocity was more than three times higher for NHESSC compared with NHEECC (0.38 vs. 0.12 m/s, p < 0.001, ES = 3.25). The key findings of this study were that SSC contributed to an enhanced NHE performance, where absolute peak knee flexor force was 13% greater for fast NHESSC compared to standard slow NHEECC. The fast NHESSC could therefore be an interesting alternative to the standard slow NHEECC execution, as it may offer potential advantages for sprint performance, as well as hamstring injury prevention and rehabilitation.

Single-leg vertical jumping in young adults with spastic cerebral palsy.

BACKGROUND: Maximum-strength tests are commonly used to detect muscle weakness in persons with cerebral palsy (CP). Tests of explosive strength (power) in the lower extremities, such as vertical jump tests, are more uncommon but might supplement maximum-strength testing by providing additional information about motor function. RESEARCH QUESTION: Is it feasible and useful to measure single-leg vertical jumping in young adults with CP? METHODS: Eleven persons with spastic CP (18-30 years), able to walk without support, were compared with a reference group. Jump height and power generation in jumping were measured using a 3D motion-analysis system and force plates. Maximum strength in plantarflexors was measured on the same occasion. Data were analysed using non-parametric statistics. RESULTS: Jump height was significantly greater in the reference group than in the group with CP, both relative to the less-involved leg of the participants with CP (p = .007) and relative to their more-involved leg (p < .001). In the group with CP, jump height was twice as great for the less-involved leg than for the more-involved leg (p = .008). Power generation at the hip joint was similar between the groups but differed for the knee and ankle joints (p = .001-.033). In the reference group, most of the power was generated at the ankle joint, while the hip was the dominant power generator for the more-involved leg in the group with CP. Muscle strength in the group with CP showed a high correlation with jump height (rho = .745, p < .001) and power generation at the ankle (rho = .780, p = .001). SIGNIFICANCE: The single-leg vertical jump test proved capable of measuring jump height and power generation in participants with CP. It also identified explosive muscle weakness both relative to a reference group and between legs. Hence the jump test may provide information additional to common tests of maximal muscle strength in persons with CP.

Differences in Peak Knee Flexor Force between Eccentric-Only and Combined Eccentric-Concentric Nordic Hamstring Exercise.

In many sports, the hamstring strain injury is a common injury. There is evidence that the Nordic hamstring exercise (NHE), a knee flexor exercise, can reduce hamstring injury risk in athletes. In research on hamstring injury prevention, eccentric-only NHE is typically performed, whereas in sports, it is relatively common for athletes to perform NHE eccentrically-concentrically. Further, NHE strength is generally assessed by measuring knee flexor force through an ankle brace, attached atop of a load cell. An alternative method might be to assess knee flexor force about the knee joint using a force plate. The aim of the study was to investigate differences in peak knee flexor force between eccentric-only and combined eccentric-concentric NHE. The purpose was also to determine the correlation between hamstring force measured at the ankle using a load cell (current gold standard) and force assessed about the knee joint using a force plate during NHE. Fifteen junior and senior elite soccer and track and field athletes (3 women and 12 men aged 17-27 years) performed eccentric NHE (ENHE) in which they leaned forward as far as possible until breakpoint and eccentric-concentric NHE (ECNHE) where they returned to the starting position. A linear encoder measured the position at which peak force occurred during the NHEs. Force assessed at the ankle differed significantly (678 vs. 600 N, p < 0.05), whereas force about the knee joint did not (640 vs. 607 N, p > 0.05) between ENHE and ECNHE (12 and 5% difference, respectively). The forward distance achieved by the participants in cm at breakpoint for ENHE was 37% higher than at the coupling phase for ECNHE (74 vs. 54 cm, p < 0.001). Very strong significant (p < 0.01) correlations were noted between peak force assessed at the ankle and about the knee joint for ENHE and ECNHE, r = 0.96 and r = 0.99, respectively. Our results suggest that ECNHE, where peak knee flexor force was reached with 37% less forward movement, may complement ENHE, i.e., during hamstring injury rehabilitation, where a position of great knee extension may not be well tolerated by the athlete. Further, assessing knee flexor force about the knee joint using a force plate may provide an alternative to measuring force at the ankle using a load cell when testing NHE strength.

Reflecting on Advances in Lower Extremity Biomechanics and Injury Prevention: Insights from Our Special Issue.

It is with great pleasure that we present this Editorial, marking the completion of our Special Issue on Lower Extremity Biomechanics and Injury Prevention [...].

Development of a Novel Nordic Hamstring Exercise Performance Test Device: A Reliability and Intervention Study.

There is evidence that a knee flexor exercise, the Nordic hamstring exercise (NHE), prevents hamstring injuries. The purpose of this study was therefore to develop, and to determine the reliability of, a novel NHE test device and, further, to determine the effectiveness of a 10-week low volume NHE program on NHE performance. Twenty female football (soccer) players, aged 16-30 years, participated in this study. From a kneeling position on the device, with the ankles secured under a heavy lifting sling, participants leaned forward in a controlled manner as far as possible (eccentric phase) and then returned to the starting position (concentric phase). A tape measure documented the forward distance achieved by the participants in cm. Participants completed three separate occasions to evaluate test-retest reliability. Additionally, 14 players performed a low volume (1 set of 5 repetitions) NHE program once weekly for 10 weeks. No significant test-retest differences in NHE performance were observed. The intra-class correlation coefficient was 0.95 and the coefficient of variation was 3.54% between tests. Mean improvement in the NHE performance test by the players following training was 22% (8.7 cm), p = 0.005. Our test device reliably measured NHE performance and is easy to perform in any setting. Further, NHE performance was improved by a 10-week low volume NHE program. This suggests that even a small dose (1 set of 5 repetitions once weekly) of the NHE may enhance NHE performance.

Full recovery of hip muscle strength is not achieved at return to sports in patients with femoroacetabular impingement surgery.

PURPOSE: The purpose of this study was to study dynamic hip  external rotation strength in patients with Femoroacetabular impingement surgery (FAI) syndrome who have undergone unilateral arthroscopic treatment and returned to sports. METHODS: A cross-sectional study was performed using an observational group (n = 22) and a matched control group (n = 22). Dynamic external rotation strength of the hip was measured using the Augustsson Strength Test, which has shown high reliability for examining side-to-side differences in hip muscle strength. RESULTS: Dynamic hip external rotation strength was significantly lower in the arthroscopically treated hip compared with the non-treated hip within the observational group (p < 0.004). CONCLUSION: This cross-sectional study shows that at return to sports, patients who have undergone unilateral arthroscopic treatment for FAI syndrome do not have adequate hip muscle strength recovery. Rehabilitation protocols should, therefore, emphasise post-operative strength training of the hip muscles. Additional research is needed to determine the consequences of reduced hip strength for the long-term outcome after arthroscopically treated FAI. CLINICAL RELEVANCE: The results of this study underline the importance of post-operative strength training prior to returning to sports in patients with femoroacetabular impingement surgery. LEVEL OF EVIDENCE: III.

Vertical drop jump landing depth influences knee kinematics in female recreational athletes.

OBJECTIVES: To examine whether different vertical drop jump (VDJ) landing depth (small versus deep) and stance width (wide versus narrow) may alter movement biomechanics in female recreational athletes. The purpose was also to identify whether leg muscle strength is a predictive factor for knee control during a VDJ. DESIGN: Cross-sectional. SETTING: Biomechanics laboratory. PARTICIPANTS: Eighteen women aged between 18 and 30 years. MAIN OUTCOME MEASURES: Three VDJ tests were used for biomechanical analysis: 1) small "bounce" jump (BJ), 2) deep "countermovement" jump with wide (CMJW) and 3) narrow foot position (CMJN). Subjects also performed an isometric knee-extension strength test, dichotomized to 'weak' versus 'strong' subjects according to median and quartiles. RESULTS: There were greater knee valgus angles during landing for both the CMJW and CMJN test compared to the BJ test (p ≤ 0.05). Differences in knee valgus between weak and strong subjects were significant for the BJ test (p = 0.044) but not for any of the other tests. CONCLUSIONS: VDJ landing depth influences knee kinematics in women. Landing depth may therefore be considered when screening athletes using the VDJ test. Also, muscle strength seems to influence the amount of knee valgus angles, but the difference was not statistically significant (except for the BJ test) in this small cohort.

A NEW CLINICAL MUSCLE FUNCTION TEST FOR ASSESSMENT OF HIP EXTERNAL ROTATION STRENGTH: AUGUSTSSON STRENGTH TEST.

INTRODUCTION: Dynamic clinical tests of hip strength applicable on patients, non-athletes and athletes alike, are lacking. The aim of this study was therefore to develop and evaluate the reliability of a dynamic muscle function test of hip external rotation strength, using a novel device. A second aim was to determine if gender differences exist in absolute and relative hip strength using the new test. METHODS: Fifty-three healthy sport science students (34 women and 19 men) were tested for hip external rotation strength using a device that consisted of a strap connected in series with an elastic resistance band loop, and a measuring tape connected in parallel with the elastic resistance band. The test was carried out with the subject side lying, positioned in 45 ° of hip flexion and the knees flexed to 90 ° with the device firmly fastened proximally across the knees. The subject then exerted maximal concentric hip external rotation force against the device thereby extending the elastic resistance band. The displacement achieved by the subject was documented by the tape measure and the corresponding force production was calculated. Both right and left hip strength was measured. Fifteen of the subjects were tested on repeated occasions to evaluate test-retest reliability. RESULTS: No significant test-retest differences were observed. Intra-class correlation coefficients ranged 0.93-0.94 and coefficients of variation 2.76-4.60%. In absolute values, men were significantly stronger in hip external rotation than women (right side 13.2 vs 11.0 kg, p = 0.001, left side 13.2 vs 11.5 kg, p = 0.002). There were no significant differences in hip external rotation strength normalized for body weight (BW) between men and women (right side 0.17 kg/BW vs 0.17 kg/BW, p = 0.675, left side 0.17 kg/BW vs 0.18 kg/BW, p = 0.156). CONCLUSIONS: The new muscle function test showed high reliability and thus could be useful for measuring dynamic hip external rotation strength in patients, non-athletes and athletes. The test is practical and easy to perform in any setting and could therefore provide additional information to the common clinical hip examination, in the rehabilitation or research setting, as well as when conducting on-the-field testing in sports. LEVEL OF EVIDENCE: 3.

Documentation of strength training for research purposes after ACL reconstruction.

PURPOSE: The purpose of this systematic literature review was to evaluate strength training protocol documentation during rehabilitation after anterior cruciate ligament (ACL) reconstruction. The aim was further to present recommendations concerning what components (i.e. methods, principles and training variables) could be considered vital to document when it comes to strength training for research purposes after ACL reconstruction. METHODS: A search of the PUBMED/MEDLINE, CINAHL and SportDiscus databases was made of relevant literature relating to strength training after ACL reconstruction. The database search was based on relevant medical subject headings terms (strength/resistance/weight training, anterior cruciate ligament reconstruction/rehabilitation). The literature was reviewed regarding the way methods and variables were documented in strength training protocols during rehabilitation after ACL reconstruction in peer-reviewed original prospective articles. RESULTS: The systematic literature search identified 139 citations published between January 1983 and May 2012. Six studies contained a strength training programme-part of the rehabilitation protocol after ACL reconstruction that met the inclusion criteria. Basic information (i.e. training frequency, intensity, volume, progression or the duration of the training period) regarding the strength training protocols used during rehabilitation after ACL reconstruction was not documented in full in four of the studies. CONCLUSION: The results clearly indicate the need of a more standardised and detailed way of documenting strength training for research purposes after ACL reconstruction in order to increase the value of future studies on this subject. This review gives recommendations on strength training protocol documentation after ACL reconstruction to facilitate this goal. LEVEL OF EVIDENCE: IV.

Variability in leg muscle power and hop performance after anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this prospective study was to describe the variability in leg muscle power and hop performance up to 2 years among patients following ACL reconstruction and specifically to illustrate the effects of various criteria for an acceptable level of muscle function. METHODS: Eighty-two patients (56 men and 26 women)with a mean age of 28 years, who underwent ACL reconstruction using either hamstring tendons (n = 46) or a patellar tendon (n = 36), were assessed pre-operatively and 3, 6, 12 and 24 months post-surgery with a battery of three lower extremity muscle power tests and a battery of three hop tests. RESULTS: Leg symmetry index (LSI) values at group level ranged between 73 and 100% at all follow-ups. When the tests were evaluated individually, patients reached an average LSI of ≥ 90% at 24 months. The success rate at 24 months for the muscle power test battery, that is,patients with an LSI of ≥ 90% in all three tests, was 48 and 44% for the hop test battery. The success rate at 24 months for both test batteries on all six muscle function tests was 22%. The criterion of an LSI of ≥ 80% resulted in 53% of the patients having an acceptable level on all six tests,while with a criterion of an LSI of ≥ 100%, none of the patients reached an acceptable level. CONCLUSION: At group level and in single muscle function tests, the muscle function outcome 1 and 2 years after ACL reconstruction is satisfactory in the present study and on a par with the results presented in the literature. However,when using more demanding criteria for a successful muscle function outcome, using batteries of tests or increasing the acceptable LSI level from ≥ 90% to ≥ 95%or ≥ 100%, the results are considered to be poor. It is suggested that this should be taken into consideration when presenting results after ACL rehabilitation, deciding on the criteria for a safe return to sports, or designing rehabilitation programmes after ACL reconstruction. LEVEL OF EVIDENCE: Prognostic prospective cohort study, Level I.

Acute effects of blood flow restriction on muscle activity and endurance during fatiguing dynamic knee extensions at low load.

The purpose of this study was to investigate muscle activity and endurance during fatiguing low-intensity dynamic knee extension exercise with and without blood flow restriction. Eleven healthy subjects with strength training experience performed 3 sets of unilateral knee extensions with no relaxation between repetitions to concentric torque failure at 30% of the 1 repetition maximum. One leg was randomized to exercise with cuff occlusion and the other leg to exercise without occlusion. The muscle activity in the quadriceps was recorded with electromyography (EMG). Ratings of perceived exertion (RPE) and acute pain were collected immediately, and delayed onset muscle soreness (DOMS) was rated before and at 24, 48, and 72 hours after exercise. The results demonstrated high EMG levels in both experimental conditions, but there were no significant differences regarding maximal muscle activity, except for a higher EMG in the eccentric phase in set 3 for the nonoccluded condition (p = 0.005). Significantly more repetitions were performed with the nonoccluded leg in every set (p < 0.05). The RPE and acute pain ratings were similar, but DOMS was higher in the nonoccluded leg (p < 0.05). We conclude that blood flow restriction during low-intensity dynamic knee extension decreases the endurance but does not increase the maximum muscle activity compared with training without restriction when both regimes are performed to failure. The high levels of muscle activity suggest that performing low-load dynamic knee extensions in a no-relaxation manner may be a useful method in knee rehabilitation settings when large forces are contraindicated. However, similarly to fatiguing blood flow restricted exercise, this method is associated with ischemic muscle pain, and thus its applications may be limited to highly motivated individuals.

The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans.

Strength training is an important component in sports training and rehabilitation. Quantification of the dose-response relationships between training variables and the outcome is fundamental for the proper prescription of resistance training. The purpose of this comprehensive review was to identify dose-response relationships for the development of muscle hypertrophy by calculating the magnitudes and rates of increases in muscle cross-sectional area induced by varying levels of frequency, intensity and volume, as well as by different modes of strength training. Computer searches in the databases MEDLINE, SportDiscus and CINAHL were performed as well as hand searches of relevant journals, books and reference lists. The analysis was limited to the quadriceps femoris and the elbow flexors, since these were the only muscle groups that allowed for evaluations of dose-response trends. The modes of strength training were classified as dynamic external resistance (including free weights and weight machines), accommodating resistance (e.g. isokinetic and semi-isokinetic devices) and isometric resistance. The subcategories related to the types of muscle actions used. The results demonstrate that given sufficient frequency, intensity and volume of work, all three types of muscle actions can induce significant hypertrophy at an impressive rate and that, at present, there is insufficient evidence for the superiority of any mode and/or type of muscle action over other modes and types of training. Tentative dose-response relationships for each variable are outlined, based on the available evidence, and interactions between variables are discussed. In addition, recommendations for training and suggestions for further research are given.

Effects of vascular occlusion on muscular endurance in dynamic knee extension exercise at different submaximal loads.

Strength training with low load under conditions of vascular occlusion has been proposed as an alternative to heavy-resistance exercise in the rehabilitation setting, when large forces acting upon the musculoskeletal system are unwanted. Little is known, however, about the relative intensity at which occlusion of blood flow significantly reduces dynamic muscular endurance and, hence, when it may increase the training effect. The purpose of this study was to investigate endurance during dynamic knee extension at different loads with and without cuff occlusion. Sixteen subjects (20-45 years of age) with strength-training experience were recruited. At 4 test sessions, the subjects performed unilateral knee extensions to failure with and without a pressure cuff around the thigh at 20, 30, 40, and 50% of their 1 repetition maximum (1RM). The pressure cuff was inflated to 200 mm Hg during exercise with occlusion. Significant differences in the number of repetitions performed were found between occluded and nonoccluded conditions for loads of 20, 30, and 40% of 1RM (p < 0.01) but not for the 50% load (p = 0.465). Thus, the application of a pressure cuff around the thigh appears to reduce dynamic knee extension endurance more at a low load than at a moderate load. These results may have implications regarding when it could be useful to apply a tourniquet in order to increase the rate of fatigue and perhaps also the resulting training effect. However, the short- and long-term safety of training under ischemic conditions needs to be addressed in both healthy and less healthy populations. Furthermore, the high acute pain ratings and the delayed-onset muscle soreness associated with this type of training may limit its potential use to highly motivated individuals.

A test battery for evaluating hop performance in patients with an ACL injury and patients who have undergone ACL reconstruction.

The purpose of this study was to develop a test battery of hop tests with high ability to discriminate (i.e. high test-retest reliability, sensitivity, specificity and accuracy) between the hop performance of the injured and the uninjured side in patients with an ACL injury and in patients who have undergone ACL reconstruction. Five hop tests were analysed: three maximum single hop tests and two hop tests while developing fatigue. Fifteen healthy subjects performed the five hop tests on three separate occasions in a test-retest design. Thirty patients, mean 11 months after an ACL injury and 35 patients, mean 6 months after ACL reconstruction were tested. ICC values ranged from 0.85 to 0.97 for the five hop tests, indicating that all the tests had high test-retest reliability. Sixty-seven percent to 100% of the healthy subjects had normal symmetry (i.e. <10% side-to-side difference) in the five hop tests. Abnormal symmetry in the five hop tests ranged from 43 to 77% for patients with an ACL injury and from 51 to 86% for patients who had undergone ACL reconstruction respectively. The three tests with the highest ability to discriminate hop performance were chosen for the test battery; they were the vertical jump, the hop for distance and the side hop. The test battery revealed a high level of sensitivity and accuracy in patients with an ACL injury (87 and 84%) and in patients who had undergone ACL reconstruction (91 and 88%), when at least one of the three tests was classified as abnormal. To summarise, the test battery consisting of both maximum single hop performances: the vertical jump and the hop for distance and hop performance while developing fatigue: the side hop, produced high test-retest reliability, sensitivity and accuracy. Further, the test battery produced higher values compared with any of the three hop tests individually revealing that only one out of ten patients had restored hop performance 11 months after an ACL injury and 6 months after ACL reconstruction. It is concluded that this test battery showed a high ability to discriminate between the hop performance of the injured and the uninjured side both in patients with an ACL injury and in patients who have undergone ACL reconstruction.

Development of a strength test battery for evaluating leg muscle power after anterior cruciate ligament injury and reconstruction.

A more sports-specific and detailed strength assessment has been advocated for patients after anterior cruciate ligament (ACL) injury and reconstruction. The purpose of this study was to develop a test battery of lower extremity strength tests with high ability to discriminate between leg power development on the injured and uninjured sides in patients after ACL injury and in patients who have undergone ACL reconstruction. Twenty-three patients were tested 6 months after ACL injury and 44 patients were tested 6 months after ACL reconstruction. Twenty-four of the 44 patients were operated on using a hamstrings graft and 20 patients were operated on using a patellar tendon graft. All the patients performed a test battery of three strength tests for each leg in a randomised order. The three strength tests were chosen to reflect quadriceps and hamstring muscular power in a knee-extension and a knee-flexion test (open kinetic chain) and lower-extremity muscular power in a leg-press test (closed kinetic chain). There was a higher sensitivity for the test battery to discriminate abnormal leg power compared with any of the three strength tests individually. Nine out of ten patients after ACL reconstruction and six out of ten of the patients after ACL injury exhibited abnormal leg power symmetry using the test battery. Thus, this test battery had high ability in terms of discriminating between the leg power performance on the injured and uninjured side, both in patients with an ACL injury and in patients who have undergone ACL reconstruction. It is concluded that a test battery consisting of a knee-extension, knee-flexion and leg-press muscle power test had high ability to determine deficits in leg power 6 months after ACL injury and reconstruction. Only a minority of the patients had restored leg muscle power. The clinical relevance is that the test battery may contribute to the decision-making process when deciding whether and when patients can safely return to strenuous physical activities after an ACL injury or reconstruction.

Ability of a new hop test to determine functional deficits after anterior cruciate ligament reconstruction.

The aim of this study was to investigate the ability of a new hop test to determine functional deficits after anterior cruciate ligament (ACL) reconstruction. The test consists of a pre-exhaustion exercise protocol combined with a single-leg hop. Nineteen male patients with ACL reconstruction (mean time after operation 11 months) who exhibited normal single-leg hop symmetry values (> or =90% compared with the non-involved extremity) were tested for one-repetition maximum (1 RM) strength of a knee-extension exercise. The patients then performed single-leg hops following a standardised pre-exhaustion exercise protocol, which consisted of unilateral weight machine knee-extensions until failure at 50% of 1 RM. Although no patients displayed abnormal hop symmetry when non-fatigued, 68% of the patients showed abnormal hop symmetry for the fatigued test condition. Sixty-three per cent exhibited 1 RM strength scores of below 90% of the non-involved leg. Eighty-four percent of the patients exhibited abnormal symmetry in at least one of the tests. Our findings indicate that patients are not fully rehabilitated 11 months after ACL reconstruction. It is concluded that the pre-exhaustion exercise protocol, combined with the single-leg hop test, improved testing sensitivity when evaluating lower-extremity function after ACL reconstruction. For a more comprehensive evaluation of lower-extremity function after ACL reconstruction, it is therefore suggested that functional testing should be performed both under non-fatigued and fatigued test conditions.

Effect of pre-exhaustion exercise on lower-extremity muscle activation during a leg press exercise.

The purpose of this study was to investigate the effect of pre-exhaustion exercise on lower-extremity muscle activation during a leg press exercise. Pre-exhaustion exercise, a technique frequently used by weight trainers, involves combining a single-joint exercise immediately followed by a related multijoint exercise (e.g., a knee extension exercise followed by a leg press exercise). Seventeen healthy male subjects performed 1 set of a leg press exercise with and without pre-exhaustion exercise, which consisted of 1 set of a knee extension exercise. Both exercises were performed at a load of 10 repetitions maximum (10 RM). Electromyography (EMG) was recorded from the rectus femoris, vastus lateralis, and gluteus maximus muscles simultaneously during the leg press exercise. The number of repetitions of the leg press exercise performed by subjects with and without pre-exhaustion exercise was also documented. The activation of the rectus femoris and the vastus lateralis muscles during the leg press exercise was significantly less when subjects were pre-exhausted (p < 0.05). No significant EMG change was observed for the gluteus maximus muscle. When in a pre-exhausted state, subjects performed significantly (p < 0.001) less repetitions of the leg press exercise. Our findings do not support the popular belief of weight trainers that performing pre-exhaustion exercise is more effective in order to enhance muscle activity compared with regular weight training. Conversely, pre-exhaustion exercise may have disadvantageous effects on performance, such as decreased muscle activity and reduction in strength, during multijoint exercise.