Knee-extension exercise's lack of immediate effect on maximal voluntary quadriceps torque and activation in individuals with anterior knee pain

Jihong Park, Terry L. Grindstaff, Joe M. Hart, Jay N. Hertel, Christopher D. Ingersoll

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Context: Weight-bearing (WB) and non-weight-bearing (NWB) exercises are commonly used in rehabilitation programs for patients with anterior knee pain (AKP). Objective: To determine the immediate effects of isolated WB or NWB knee-extension exercises on quadriceps torque output and activation in individuals with AKP. Design: A single-blind randomized controlled trial. Setting: Laboratory. Participants: 30 subjects with self-reported AKP. Interventions: Subjects performed a maximal voluntary isometric contraction (MVIC) of the quadriceps (knee at 90°). Maximal voluntary quadriceps activation was quantified using the central activation ratio (CAR): CAR = MVIC/(MVIC + superimposed burst torque). After baseline testing, subjects were randomized to 1 of 3 intervention groups: WB knee extension, NWB knee extension, or control. WB knee-extension exercise was performed as a sling-based exercise, and NWB knee-extension exercise was performed on the Biodex dynamometer. Exercises were performed in 3 sets of 5 repetitions at approximately 55% MVIC. Measurements were obtained at 4 times: baseline and immediately and 15 and 30 min postexercise. Main Outcome Measures: Quadriceps torque output (MVIC: N·m/Kg) and quadriceps activation (CAR). Results: No significant differences in the maximal voluntary quadriceps torque output (F 2,27 = 0.592, P =.56) or activation (F 2,27 = 0.069, P =.93) were observed among the 3 treatment groups. Conclusions: WB and NWB knee-extension exercises did not acutely change quadriceps torque output or activation. It may be necessary to perform exercises over a number of sessions and incorporate other disinhibitory interventions (eg, cryotherapy) to observe acute changes in quadriceps torque and activation.

Original languageEnglish (US)
Pages (from-to)119-126
Number of pages8
JournalJournal of Sport Rehabilitation
Issue number2
StatePublished - May 2012

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Rehabilitation


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