Experimental knee joint pain during strength training and muscle strength gain in healthy subjects: A randomized controlled trial

Abstract

Objective. Knee joint pain and reduced quadriceps strength are cardinal symptoms in many knee pathologies. In people with painful knee pathologies, quadriceps exercise reduces pain, improves physical function, and increases muscle strength. A general assumption is that pain compromises muscle function and thus may prevent effective rehabilitation. This study evaluated the effects of experimental knee joint pain during quadriceps strength training on muscle strength gain in healthy individuals. Methods. Twenty-seven healthy untrained volunteers participated in a randomized controlled trial of quadriceps strengthening (3 times per week for 8 weeks). Participants were randomized to perform resistance training either during pain induced by injections of painful hypertonic saline (pain group, n ‫؍‬ 13) or during a nonpainful control condition with injection of isotonic saline (control group, n ‫؍‬ 14) into the infrapatellar fat pad. The primary outcome measure was change in maximal isokinetic muscle strength in knee extension/flexion (60, 120, and 180 degrees/second). Results. The group who exercised with pain had a significantly larger improvement in isokinetic muscle strength at all angular velocities of knee extension compared to the control group. In knee flexion there were improvements in isokinetic muscle strength in both groups with no between-group differences. Conclusion. Experimental knee joint pain improved the training-induced gain in muscle strength following 8 weeks of quadriceps training. It remains to be studied whether knee joint pain has a positive effect on strength gain in patients with knee pathology.

Muscle Strength and Changes in Physical Function in Women With Systemic Lupus Erythematosus

“…Lower extremity muscle strength was assessed by knee torque. A Biodex unit (Biodex Medical Systems) was used to measure peak isokinetic torques of knee extension and flexion at 120 degrees/second, adjusted for body weight . Participants completed 2 reproducible and acceptable trials.…”

Muscle Strength, Muscle Mass, and Physical Disability in Women With Systemic Lupus Erythematosus

“…A Biodex® unit was used to measure peak isokinetic torques of knee extension and flexion at 120 degrees/second adjusted for body weight (34). Participants completed two reproducible and acceptable trials.…”

A Review of the Relationships Between Knee Pain and Movement Neuromechanics

“…The EKP decreases maximal knee-extension force, torque, and force steadiness during maximal voluntary isometric, concentric, and eccentric muscle actions. 9,[11][12][13][18][19][20][21][22] The EKP immediately reduces maximal knee extensor peak torque 5% to 15% during eccentric muscle action, 18,21 10% to 34% during isometric muscle action, 9,11,13,18 and 7% to 22% during concentric muscle action. 18,21,22 Reduced concentric and eccentric knee-extension strength likely results in decreased knee-extension torque during common activities, including walking and running (concentric and eccentric) and jumping (concentric) and landing (eccentric).…”

“…9,[11][12][13][18][19][20][21][22] The EKP immediately reduces maximal knee extensor peak torque 5% to 15% during eccentric muscle action, 18,21 10% to 34% during isometric muscle action, 9,11,13,18 and 7% to 22% during concentric muscle action. 18,21,22 Reduced concentric and eccentric knee-extension strength likely results in decreased knee-extension torque during common activities, including walking and running (concentric and eccentric) and jumping (concentric) and landing (eccentric). When knee-extension torque is reduced, individuals may decrease knee-flexion angle during eccentric muscle actions, like the weight acceptance phase of gait, resulting in less energy absorbed via the knee extensors and more energy absorbed by the skeletal system.…”