Bellicha A1, Yebenes B1, Giroux C1, Ciangura C2, Thoumie P3, Oppert J-M2, Portero P1
1University Paris-Est Créteil, Laboratory Bioengineering, Tissus and Neuroplasticity (BIOTN, EA 7377), Créteil, France, 2Sorbonne University, Assistance Publique-Hôpitaux de Paris (AP-HP), Pitié-Salpêtrière Hospital, Department of Nutrition, Paris, France, 3Sorbonne University, Assistance Publique-Hôpitaux de Paris (AP-HP), Rothschild hospital, Department of Physical and Rehabilitation Medicine, Paris, France
Background: The prevalence of obesity has markedly increased in the US and worldwide in the last decades. Physical activity is widely recommended to maintain overall health and physical fitness in subjects with obesity. Accurate assessment of physical fitness, including muscle strength, is important to individualize physical activity prescription and to evaluate the effectiveness of physical activity programs. Isokinetic dynamometry is the gold-standard method for the assessment of muscle strength. However, using isokinetic testing in the routine management of subjects with obesity is challenging because of time constraints and difficulties with subject positioning and alignment of the knee and dynamometer rotational axis. Force platforms provide a reliable and valid assessment of lower-limb muscle strength and power in healthy subjects or in older adults but have not been assessed in subjects with obesity.
Purpose: This study aimed to assess in subjects with severe obesity
1) the reliability of a force platform for assessing muscle strength and power;
2) its validity against isokinetic dynamometer;
3) relations between muscle strength and power assessed either with a force platform or isokinetic dynamometer and lean body mass.
Methods: Twenty women with severe obesity (body mass index ≥40 kg.m-2) were recruited at our academic medical center (Department of Nutrition, Pitie-Salpetriere university hospital, Paris, France). Lower-limb muscle strength and power were assessed with a force platform (Kistler). Subjects were asked to perform two consecutive countermovement jumps (CMJs). Maximal instantaneous force of each trial was recorded for analyses. Additionally, knee extension torque was assessed with isokinetic testing at 240°.s-1 (Con-Trex) and lean body mass with DXA absorptiometry. Intraclass coefficient correlations were calculated to assess reliability of the force platform testing. Pearson correlations were used to assess validity of the force platform testing against isokinetic strength and associations with lean body mass.
Results: Mean (SD) age was: 42.3 (11.2) years, BMI: 44.0 (4.6) kg.m-2, lean body mass: 56.3 (8.0) kg, maximal power during CMJ: 2,064 (560) W, maximal force during CMJ: 2,034 (289) N, isokinetic knee extension torque: 89 (18) Nm. For both power and force values, high reproducibility was observed between the two consecutive CMJs (ICC [CI 95%]: 0.95 [0.88-0.99] and 0.90 [0.77-0.96], respectively). Maximal power and force during CMJ were associated with isokinetic torque (r2=0.55, P 0.001 and r2=0.45, P=0.002). Lean body mass was strongly associated with maximal force during CMJ (r2=0.83, P 0.001) and moderately associated with power during CMJ (r2=0.53, P 0.001) or isokinetic torque (r2=0.40, P=0.005).
Conclusion(s): The force platform appears to be a reliable and valid tool for assessing muscle strength and power in subjects with obesity. Strength values measured with the force platform appear to be more strongly associated with lean body mass than isokinetic strength. This emphasizes the importance of assessing muscle strength during multi-joints movements, known to be more tightly linked to physical function than single-joint movements.
Implications: Force platforms represent an easy-to-implement tool to assess lower-limb muscle strength and power in clinical settings. Further studies are needed to establish normative values in patients with obesity.
Keywords: Obesity, muscle power, force platform
Funding acknowledgements: This study was supported by the Institute of Cardiometabolism and Nutrition (ICAN, Paris, France)
Purpose: This study aimed to assess in subjects with severe obesity
1) the reliability of a force platform for assessing muscle strength and power;
2) its validity against isokinetic dynamometer;
3) relations between muscle strength and power assessed either with a force platform or isokinetic dynamometer and lean body mass.
Methods: Twenty women with severe obesity (body mass index ≥40 kg.m-2) were recruited at our academic medical center (Department of Nutrition, Pitie-Salpetriere university hospital, Paris, France). Lower-limb muscle strength and power were assessed with a force platform (Kistler). Subjects were asked to perform two consecutive countermovement jumps (CMJs). Maximal instantaneous force of each trial was recorded for analyses. Additionally, knee extension torque was assessed with isokinetic testing at 240°.s-1 (Con-Trex) and lean body mass with DXA absorptiometry. Intraclass coefficient correlations were calculated to assess reliability of the force platform testing. Pearson correlations were used to assess validity of the force platform testing against isokinetic strength and associations with lean body mass.
Results: Mean (SD) age was: 42.3 (11.2) years, BMI: 44.0 (4.6) kg.m-2, lean body mass: 56.3 (8.0) kg, maximal power during CMJ: 2,064 (560) W, maximal force during CMJ: 2,034 (289) N, isokinetic knee extension torque: 89 (18) Nm. For both power and force values, high reproducibility was observed between the two consecutive CMJs (ICC [CI 95%]: 0.95 [0.88-0.99] and 0.90 [0.77-0.96], respectively). Maximal power and force during CMJ were associated with isokinetic torque (r2=0.55, P 0.001 and r2=0.45, P=0.002). Lean body mass was strongly associated with maximal force during CMJ (r2=0.83, P 0.001) and moderately associated with power during CMJ (r2=0.53, P 0.001) or isokinetic torque (r2=0.40, P=0.005).
Conclusion(s): The force platform appears to be a reliable and valid tool for assessing muscle strength and power in subjects with obesity. Strength values measured with the force platform appear to be more strongly associated with lean body mass than isokinetic strength. This emphasizes the importance of assessing muscle strength during multi-joints movements, known to be more tightly linked to physical function than single-joint movements.
Implications: Force platforms represent an easy-to-implement tool to assess lower-limb muscle strength and power in clinical settings. Further studies are needed to establish normative values in patients with obesity.
Keywords: Obesity, muscle power, force platform
Funding acknowledgements: This study was supported by the Institute of Cardiometabolism and Nutrition (ICAN, Paris, France)
Topic: Human movement analysis; Human movement analysis
Ethics approval required: Yes
Institution: Assistance Publique-Hôpitaux de Paris
Ethics committee: Comite de Protection des Personnes Sud-Est III, Bron, France
Ethics number: Clinical Trials NCT03325764
All authors, affiliations and abstracts have been published as submitted.
