Damage to the human quadriceps muscle from eccentric exercise and the training effect

Abstract

Nine participants performed two bouts of a step exercise, during which the quadriceps muscle of one leg acted eccentrically. Before and after the exercise, isokinetic torque was measured over a range of knee angles to determine the optimum angle for torque. Immediately after the first bout of exercise, the quadriceps showed a significant (P < 0.05) shift of 15.6 +/- 1.4 degrees (mean +/-sx) of its optimum angle in the direction of longer lengths, suggesting the presence of damage. A drop in peak torque, together with delayed soreness and swelling, confirmed that damage to muscle fibres had occurred. After the second bout of exercise, 8 days later, the shift in optimum angle was 10.4 +/- 1.0 degrees, which was significantly less than after the first bout (P < 0.05). Other indicators of damage were also reduced. In addition, the muscle exhibited a sustained shift in optimum angle (3.4 +/- 0.9 degrees), suggesting that some adaptation had taken place after the first bout of exercise. We conclude that muscles like the quadriceps can show evidence of damage after a specific programme of eccentric exercise, followed by an adaptation response. This is despite the fact that the quadriceps routinely undergoes eccentric contractions in everyday activities.

Massage Timing Affects Postexercise Muscle Recovery and Inflammation in a Rabbit Model

“…Delayed onset muscle soreness (DOMS) is characterized by skeletal muscle strength loss, soreness, swelling, and weakness are known to accompany intense or prolonged physical activity, particularly EEX (3, 4). DOMS is thought to be the result of a delayed secondary inflammatory response to a primary mechanical disruption that arguably leads to further injury (44, 17).…”

Effect of plyometric training on the fascicle length of the gastrocnemius medialis muscle

“…Some evidence for the lengthening of the FL is available 16,[20][21][22][23][24][25][26] . However, to the best of our knowledge, this is the first study to show increases in the FL by PT.…”

“…This is important in improving performance. Increasing the FL by eccentric training is recognized to promote an optimum angle and length 21,22) shift and improvement in eccentric peak torque 20) , which was purported to be related to an increase in elastic energy storage capacity. In addition, it was considered that the increase in FL is important not only for improving performance, but also for the prevention of injuries such as muscle strain, because the muscles can work more efficiently without exposure to overstretching.…”

Trigger point dry needling, manual therapy and exercise versus manual therapy and exercise for the management of Achilles tendinopathy: a feasibility study

“…Neurological adaptations include 1) broader and faster cortical activity during movements; 2) inversed motor unit activation; 3) increased cross over effect; 4) faster neural adaptations to resistance training; 5) attenuated muscle sympathetic nerve activity; 6) decreased EMG amplitude at similar force levels; and 7) greater EMG signal prior to onset of movement. [110][111][112] Mechanical adaptations of eccentric contractions include 1) higher absolute force of contraction; 2) decreased fatigability; 3) lower cardiopulmonary responses; 4) increased metabolic efficiency; and 5) training effect for eccentric exercise with reduced pain following subsequent eccentric training sessions. 110 Changes to the Achilles tendon in healthy subjects have been reported after 4 weeks of training.…”

“…113 Injury can occur to the muscle fiber from eccentric training. 111,113,114 Muscles unaccustomed to eccentric exercise are susceptible to delayed onset muscle soreness which is characterized by soreness and stiffness generally developing 24 hours after the activity.…”