Abstract
Objectives
To validate muscle endurance estimation and to examine relationships with dependency and inflammation in elderly persons.
Design
Cross sectional validation and explorative study.
Setting
Hospitalized geriatric patients and community-dwelling controls.
Participants
91 elderly patients (aged 83±5 years), 100 elderly controls (aged 74±5 years) and 100 young controls (aged 23±3 years).
Measurements
Grip strength (GS) was recorded continuously during sustained maximal contraction until exhaustion. Fatigue resistance (FR) was expressed as the time during which GS drops to 50% of its maximum. Grip work (GW) was estimated as GW=GS*0.75*FR, and compared to the measured GW. In the elderly participants, relationships (controlling for age and physical activity) of GS, FR, GW and GW corrected for body weight (GW/BW) with dependency (Katz-scale) and inflammation (circulating IL-6 and TNF-alpha) were analyzed.
Results
Excellent correlation between estimated and measured GW was found (r=0.98, p<0.001). The method error coefficient of variance was 10% for all participants; 7% for all elderly and 8% for young controls. Better GS, FR, GW and GW/BW was significantly related with less dependency (all p<0.05 or p<0.01, except for FR in the male) and with lower circulating IL-6 (all p<0.05 or p<0.01, except for GS in both genders). Higher IL-6 was significantly related to worse dependency (p<0.01). No significant relationships with TNF-alpha were found.
Conclusion
GW estimation is a valid parameter reflecting muscle endurance in elderly persons presenting diverse clinical conditions. GW is significantly related to both dependency and circulating IL-6, and is a promising outcome parameter in comprehensive geriatric assessment.
