Agonist versus antagonist muscle fatigue effects on thigh muscle activity and vertical ground reaction during drop landing

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Abstract

Background

Agonist and antagonist co-activation plays an important role for stabilizing the knee joint, especially after fatigue. However, whether selective fatigue of agonists or antagonist muscles would cause different changes in muscle activation patterns is unknown.

Hypothesis

Knee extension fatigue would have a higher influence on landing biomechanics compared with a knee flexion protocol.

Study design

Repeated-measures design.

Methods

Twenty healthy subjects (10 males and 10 females) performed two sets of repeated maximal isokinetic concentric efforts of the knee extensors (KE) at 120° s−1 until they could no longer consistently produce 30% of maximum torque. On a separate day, a similar knee flexion (KF) fatigue protocol was also performed. Single leg landings from 30 cm drop height were performed before, in the middle and after the end of the fatigue test. The mean normalized electromyographic (EMG) signal of the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and gastrocnemius (GAS) at selected landing phases were determined before, during and after fatigue. Quadriceps:hamstrings (Q:H) EMG ratio as well as sagittal hip and knee angles and vertical ground reaction force (GRF) were also recorded.

Results

Two-way analysis of variance designs showed that KE fatigue resulted in significantly lower GRF and higher knee flexion angles at initial contact while maximum hip and knee flexion also increased (p < 0.05). This was accompanied by a significant decline of BF EMG, unaltered EMG of vastii and GAS muscles and increased Q:H ratio. In contrast, KF fatigue had no effects on vGRFs but it was accompanied by increased activation of VM, BF and GAS while the Q:H increased during before landing and decreased after impact.

Conclusion

Fatigue responses during landing are highly dependent on the muscle which is fatigued.

Introduction

Landing from a jump is a common activity in sport and work environments. The vertical ground reaction force (GRF) during single-leg landings is high and it can reach 11 times body weight (McNitt-Gray, 1991). This mechanical shock must be attenuated by the musculoskeletal system. However, when the external loads are very high for the body to adequately attenuate, the probability of injury increases (Devita and Skelly, 1992, Dufek et al., 1990, Dufek and Bates, 1991, Gross and Nelson, 1988, James et al., 2000, Kovacs et al., 1999).

Fatigue has been hypothesized to alter the biomechanical and neuromuscular factors associated with the risk of sustaining musculoskeletal injury (Christina et al., 2001, Rozzi et al., 1999a). Epidemiological and experimental studies indicate that fatigue combined with extreme loads, may lead to injury (Pettrone and Ricciardelli, 1987, Urabe et al., 2005). Fatigue affects reaction time (Hakkinen and Komi, 1986), movement co-ordination and motor control precision (Sparto et al., 1997), and reduces the muscle force generation capacity (Nicol et al., 1991a).

The ground reaction force (GRF) provides an indication of the loading of the musculoskeletal system after fatigue; more importantly, because the GRF is greater during a stiffer landing, GRF has be used to identify changes in landing stiffness (Madigan and Pidcoe, 2003, Padua et al., 2006, Tillman et al., 2004). Research has shown that vertical GRF during single-leg landing decreases after fatigue (Madigan and Pidcoe, 2003) while vertical leg stiffness remains unaltered (Padua et al., 2006). The reduction of vertical GRF after fatigue is indicative of the subject effort to reduce the mechanical shock due to landing.

Since landing is a multiarticular task, subjects may use altered activation and movement strategies to account for fatigue effects. Previous research has shown that post-fatigue landing is characterised by increased flexion of the knee (Coventry et al., 2006, Madigan and Pidcoe, 2003) and the hip (Coventry et al., 2006) and decreased ankle plantarflexion (Coventry et al., 2006). An increase in knee flexion acceleration has also been reported (Fagenbaum and Darling, 2003). Fatigue also caused a re-distribution of work produced around the lower limb joints, as hip joint work increased, knee joint remained unaltered while ankle work decreased after fatigue (Coventry et al., 2006, Madigan and Pidcoe, 2003).

The alterations in kinetics and kinematics after fatigue may be the result of alterations in muscle activation profiles of the associated musculature. Despite this, only a few studies have examined muscle activation profiles during single-leg landings after fatigue (Padua et al., 2006, Rozzi et al., 1999b). Particularly, increased co-contraction of antagonistic musculature around the knee and the ankle (Padua et al., 2006) and alterations in contraction onset of knee and ankle muscles (Rozzi et al., 1999b) have been reported. Among numerous strategies available, Padua et al. (2006) identified three strategies to control joint motion after fatigue: the ankle-dominant strategy where individuals place greater reliance on the ankle musculature; the antagonist inhibition strategy which is characterised by a decline in antagonist muscle activation patterns upon landing and, finally, the quadriceps-dominant strategy where subjects place greater reliance on quadriceps muscles after fatigue. It seems, therefore, muscle activation responses to fatigue mainly focus around the activity patterns of the quadriceps and hamstrings. However, it is known that these co-contraction of the agonist–antagonist muscle groups around the knee is an important determinant of knee joint stability (Kellis, 1998). For these reasons, examination of fatigue effects on activation of agonist–antagonist couple of muscles is worthwhile.

Evidence suggests that agonist fatigue affects movement kinematics more than antagonist muscle fatigue (Jaric et al., 2000, Rodacki et al., 2002). For example, Rodacki et al. (2002) reported that fatiguing the knee flexor muscles did not change the kinematic, kinetic, and electromyographic profiles of counter movement jumps. In contrast, knee extensor fatigue caused the subjects to adjust several variables of the movement. These results, however, apply to countermovement jumps where individuals aim to maximize jumping performance. This differs compared with drop landings where safe landing is the main priority. Single-leg landings are characterised by high pre-activation of vastus medialis, hamstrings and lateral gastrocnemius muscles (Cowling and Steele, 2001, Tillman et al., 2004) in order to stabilize the knee and the ankle in preparation for landing. The majority of previous studies examined landing biomechanics after fatiguing mainly the knee extensor musculature (Fagenbaum and Darling, 2003, Madigan and Pidcoe, 2003, Padua et al., 2006, Rozzi et al., 1999b, Wikstrom et al., 2004). To our knowledge, muscle activation and kinematics during singe leg landing following different muscle fatigue protocols have not been examined. Taken into account the potentially different roles of agonist and antagonist muscle action during landing, it can be assumed that selective fatigue of either of them would cause different changes in movement biomechanics. Such information may provide an insight on the way the neuromuscular system adjusts the movement co-ordination pattern used during landing under fatigue of different muscles. The objective of this study was to compare the effects of a knee extension (KE) and flexion (KF) fatigue protocol on vertical GRF and EMG characteristics during landing. It was hypothesized that KE fatigue would have a higher influence on vertical GRF, kinematic and EMG variables compared with KF protocol.

Section snippets

Design

A single two-group pre-post test design was applied. The subjects visited the laboratory three days, a week apart. The aim of the first visit was to familiarize the subjects with isokinetic dynamometer and landing technique. Day 1 was a familiarisation session whereas the KE (agonist) and KF (antagonist) isokinetic fatigue protocols were performed on the next two sessions on a random basis. Vertical GRF, muscle EMGs and hip and knee kinematics were recorded prior to and after fatigue.

Subjects

Ten males

Results

The ANOVA results are presented in Table 1. Significant fatigue × protocol interaction effects were found for GRF values, MAXHIP, EMGBF during the PR and LR1 phases, EMGVM and EMGVL during the PR phase, EMGGAS during the LR1 and LR2 phases and quadriceps:hamstrings co-activation ratio during the LR1 phase.

Discussion

The primary finding of this study is that landing responses to fatigue differ between KE and KF fatigue protocols. KE fatigue caused a decline in GRF values, increased knee flexion angle and reduced hamstrings activation, unaltered activation of vastii muscles and increased Q:H ratio. In contrast, KF fatigue did not alter GRF values but it caused alterations in VM, GAS and BF activity while the Q:H declined during the loading response phase.

Eleftherios Kellis completed his B.Ed. in Physical Education and Sport Sciences, at the Aristotle University of Thessaloniki, Greece (1993) and his Ph.D. at the Department of Movement Sciences and Physical Education, University of Liverpool, England (1996). From 1996 to 1999 he was a Lecturer in Sports Biomechanics in the Division of Sport Sciences at the University of Northumbria at Newcastle, England. In 2001, he joined the Department of Physical Education and Sports Sciences at Serres at the

References (42)

  • P. Devita et al.

    Effect of landing stiffness on joint kinetics and energetics in the lower extremity

    Med Sci Sport Exerc

    (1992)
  • J.S. Dufek et al.

    Biomechanical factors associated with injury during landing in jump sports

    Sport Med

    (1991)
  • J. Dufek et al.

    Lower extremity moments of force during landings

    Med Sci Sport Exerc

    (1990)
  • R. Fagenbaum et al.

    Jump landing strategies in male and female college athletes and the implications of such strategies for anterior cruciate ligament injury

    Am J Sport Med

    (2003)
  • T. Gross et al.

    The shock attenuation role of the ankle during landing from a vertical jump

    Med Sci Sport Exerc

    (1988)
  • K. Hakkinen et al.

    Electromyographic and force production characteristics of leg extensor muscles of elite weight lifters during isometric, concentric and various stretch-shortening cycle exercises

    Int J Sport Med

    (1986)
  • T. Hewett et al.

    Plyometric training in female athletes. Decreased impact forces and hamstring torques

    Am J Sport Med

    (1996)
  • C.R. James et al.

    Effects of injury proneness and task difficulty on joint kinetic variability

    Med Sci Sport Exerc

    (2000)
  • S. Jaric et al.

    Changes in movement final position associated with agonist and antagonist muscle fatigue

    Eur J Appl Phys

    (2000)
  • E. Kellis

    Quantification of quadriceps and hamstring antagonist activity

    Sport Med

    (1998)
  • I. Kovacs et al.

    Foot placement modifies kinematics and kinetics during drop jumping

    Med Sci Sport Exerc

    (1999)
  • Eleftherios Kellis completed his B.Ed. in Physical Education and Sport Sciences, at the Aristotle University of Thessaloniki, Greece (1993) and his Ph.D. at the Department of Movement Sciences and Physical Education, University of Liverpool, England (1996). From 1996 to 1999 he was a Lecturer in Sports Biomechanics in the Division of Sport Sciences at the University of Northumbria at Newcastle, England. In 2001, he joined the Department of Physical Education and Sports Sciences at Serres at the Aristotle University of Thessaloniki, where currently teaches statistics and biomechanics. His main research interests are in the area of muscle co-ordination via electromyography in clinical and sport applications.

    Vasiliki Kouvelioti completed her B.Ed. in Physical Education and Sports Sciences (2001) and received her Master degree on Exercise and Health from the Department of Physical Education and Sports Sciences at Serres, Aristotle University of Thessaloniki, Greece (2004). She is currently a Doctoral student at the same department and her main research interest is in the biomechanics of therapeutic exercises, fatigue effects on performance and clinical biomechanics applications.

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