Grip Work Measurement with the Jamar Dynamometer: Validation of a Simple Equation for Clinical Use.

OBJECTIVES: Previously, we developed and validated an easy test to measure muscle fatigability during sustained maximal handgrip contraction in older persons using a Martin Vigorimeter device. This study aimed at validating the equation to estimate grip work (GW) during sustained maximal handgrip contraction, by monitoring continuously the grip strength (GS) decay using a Jamar Dynamometer-like (JD) device. DESIGN: Cross sectional, explorative study. SETTING: Data collection took place at The National Research Centre for the Working Environment in Copenhagen, Denmark. PARTICIPANTS: 962 subjects, belonging to a subgroup of the Copenhagen Aging and Midlife Biobank, were enrolled. METHODS: GS was recorded continuously during sustained maximal contraction until it dropped to 50% of its maximum and fatigue resistance (FR, time to fatigue) was noted. GW, area under the force-time curve, was compared to its estimate which was calculated as GWestimated=GSmax*0.75*FR. RESULTS: Excellent correlation was found between GWestimated and GWmeasured (R²=0.98 p<0.001). The equation slightly overestimated GW by 6.04 kg*s (95% CI[-0.08, 12.15]) with a coefficient of variation method error of 6%. CONCLUSION: GW estimation is a valid parameter reflecting muscle work output during a sustained maximal grip effort in healthy middle-aged community-dwelling persons when using a JD. GW estimation is a promising outcome parameter in comprehensive geriatric assessment and its validation for commonly used instruments in geriatric practice will increase its clinical implementation.

Force-time characteristics during sustained maximal handgrip effort according to age and clinical condition.

BACKGROUND: Muscle fatigue, a prominent symptom in older patients, can be assessed by sustained maximal handgrip testing. The force decline during sustained maximal contraction is described for young adults, but data for elderly persons are scarce. The aim of this study was to investigate force-time characteristics during a sustained maximal handgrip effort according to age and clinical condition. METHODS AND MATERIALS: Force-time data were continuously recorded during sustained maximal grip effort in 91 elderly patients (aged 83±5years), 100 elderly controls (aged 74±5years) and 100 young controls (aged 23±3years). The force-time curve was divided in 4 parts per 25% strength drop observed. Time (representing fatigue resistance (FR)) was measured during which grip strength (GS) dropped to 75% (FR75), 50% (FR50), 25% (FR25) of its maximum and to exhaustion (FRexhaustion). Grip work ((GW), the area under the force-time curve) was measured for the 4 parts as well as for the first 20 and 30s of the fatigue protocol test. Strength decay (GWdecay), defined as the difference between the area under the curve (% GW) and a theoretical maximal area under the curve (assuming there's no strength drop), was also studied. In the elderly participants, relationships (controlling for age and sex) of GS, FR and GW with circulating IL-6 and TNF-α were analyzed. RESULTS: FRexhaustion was similar for all groups, whereas the duration of each of the 4 parts was significantly different between the 3 groups. FR75 was shortest in old patients (p=0.004), FR75-50 was almost twice as long in old community-dwelling compared to old patients and young controls (p<0.001). This contrast was inverted for FR50-25 which was significantly shorter in old community-dwelling compared to the other groups (p=0.013). FR25-exhaustionwas significantly longer in young controls compared to the groups of older participants (p=0.017). Old patients showed lower GW for the first 2 parts compared to old community-dwelling and young controls. Also, GWdecay values during the first 20 and 30s were significantly higher in old patients compared to old community-dwelling and young controls (both p<0.001). IL-6 was significantly related to lower GSmax, FR75, FR50, FR25, FRexhaustion, GW75, GW50 and GW75-50. CONCLUSION: This is the first study reporting differences in strength decay during a sustained maximal handgrip effort according to age and clinical condition. Old patients showed a particularly rapid decline in GW during the first part of sustained handgrip. GW was also significantly related to circulating IL-6. Future studies should confirm whether a shorter FR test protocol (i.e. until FR75) but using a continuous registration of the strength decay could be more informative in a clinical setting compared to the classical FR test (measuring only FR50).

Recovery of muscular performance after surgical stress in elderly patients.

INTRODUCTION: Inflammation is related to muscle wasting in elderly persons. Since surgery is accompanied by an important inflammatory response, the degree of muscle wasting and related symptoms such as weakness and tiredness might exacerbate very rapidly in elderly surgery patients. METHODS: PubMed and Web of Science were systematically screened for articles reporting the influence of surgery-induced inflammation on muscle performance and/or fatigue in elderly patients. Studies reporting surgery-induced inflammation and changes in muscle performance and/or fatigue, but without analyzing their association were excluded. Although 5 relevant articles were identified including older patients (highest ages reported were 71-92 years), none focused exclusively on elderly patients. Only 2 studies assessed muscle performance, and in none muscle mass was evaluated. Overall, we found evidence that in elderly patients higher surgery-induced inflammation was significantly related to worse muscle performance and fatigue in the first postoperative days as well as after more than one month (especially for fatigue) following the intervention. Pre-operative anti-inflammatory treatment using steroids or glucocorticoids can reduce the surgery-induced inflammatory response and improve the recovery of muscle performance and postoperative fatigue in elderly elective abdominal surgery or arthroplasty patients. CONCLUSION: We can conclude that to date, only few studies have investigated the association between surgery-induced inflammation and changes in postoperative muscle performance and fatigue in elderly patients. More research is warranted focusing on both the short -and long-term effects of surgical stress on muscle performance in elderly patients as well as the on risks and benefits of peri-operative anti-inflammatory treatment.