Comparison between Two Different Handgrip Systems and Protocols on Force Reduction in Handgrip Assessment.

INTRODUCTION: Fatigue resistance (FR) can be assessed as the time during which grip strength (GS) drops to 50% of its maximum during a sustained maximal voluntary contraction. For the first time, we compared force-time characteristics during FR test between two different handgrip systems and investigated age- and clinical-related differences in order to verify if a briefer test protocol (i.e., until 75%) could be sufficiently informative. METHODS: A cohort of young healthy controls (Y, <30 y, 24 ± 3 y, 54% women), middle-aged (MA, 30-65 y, 47 ± 11 y, 54% women), and older (OLD, >65 y, 77 ± 7 y, 50% women) community-dwelling persons, and hospitalized geriatric patients (HOSP, 84 ± 5 y, 50% women) performed the FR test. For this purpose, an adapted vigorimeter (original rubber bulb of the Martin Vigorimeter connected to a Unik 5000 pressure gauge) here defined as "pneumatic handgrip system" (Pneu) and Dynamometer G200 system (original Jamar Dynamometer handle with an in-build strength gauge) here defined as "hydraulic handgrip system" (Hydr) were used. Force-time curves were analysed from 100% to 75% and from 75% to 50% of the initial maximal GS during the FR test. The area under the curve (GW) was calculated by integrating the actual GS at each time interval (i.e., 1/5,000 s) and corrected for body weight (GW/body weight). RESULTS: For both systems, we found fair associations between FR100-50 and FR100-75 (Pneu mean difference = 50.1 s [95% CI: 47.9-52.4], r2 = 0.48; Hydr mean difference = 28.4 s [95% CI: 27.0-29.7], r2 = 0.52, all p < 0.001) and also moderate associations between GW(100-50)/body weight and GW(100-75)/body weight (Pneu mean difference = 32.1 kPa*s/kg [95% CI: 30.6-33.6], r2 = 0.72; Hydr mean difference = 8.1 kg*s/kg [95% CI: 7.7-8.6], r2 = 0.68, all p < 0.001). Between MA and OLD, we found a significant age-related difference in the GW results in the first 25% strength decay for Pneu (10.2 ± 0.6 kPa*s/kg against 7.1 ± 1.2 kPa*s/kg, respectively). CONCLUSION: The brief test protocol is valid. Differences within the first 25% strength decay in GW between OLD and HOSP were identified when using Pneu but not when using Hydr. Therefore, a brief FR test protocol using a continuous registration of the strength decay seems to be sufficiently informative in a clinical setting to appraise muscle fatigability, however, only when using a Pneu system.

Validity and reliability of Eforto®, a system to (self-)monitor grip strength and muscle fatigability in older persons.

INTRODUCTION: We developed Eforto®, an innovative system for (self-)monitoring of grip strength (GS) and muscle fatigability (Fatigue Resistance (FR = time until GS decreased to 50% of maximum during sustained contraction) and grip work (GW = area under the strength-time curve)). The Eforto® system consists of a rubber bulb that is wirelessly connected to a smartphone-based application, and a telemonitoring platform. The aim was to evaluate the validity and reliability of Eforto® to measure muscle fatigability. METHODS: Community-dwelling older persons (n = 61), geriatric inpatients (n = 26) and hip fracture patients (n = 25) were evaluated for GS and muscle fatigability. In community dwellers fatigability was tested twice in the clinic (once with Eforto®, once with Martin Vigorimeter (MV), standard analog handgrip system) and for six consecutive days as a self-assessment at home with Eforto®. In hospitalized participants, fatigability was tested twice using Eforto®, once by a researcher and once by a health professional. RESULTS: Criterion validity was supported by good to excellent correlations between Eforto® and MV for GS (r = 0.95) and muscle fatigability (FR r = 0.81 and GW r = 0.73), and no significant differences in measurements between both systems. Inter-rater and intra-rater reliability for GW were moderate to excellent (intra-class correlation: 0.59-0.94). The standard error of measurement for GW was small for geriatric inpatients and hip fracture patients (224.5 and 386.5 kPa*s) and higher for community-dwellers (661.5 kPa*s). DISCUSSION/CONCLUSION: We established the criterion validity and reliability of Eforto® in older community-dwelling persons and hospitalized patients, supporting the implementation of Eforto® for (self-)monitoring of muscle fatigability.

Six weeks of strength endurance training decreases circulating senescence-prone T-lymphocytes in cytomegalovirus seropositive but not seronegative older women.

BACKGROUND: Ageing is associated with a decline in immune function termed immunosenescence. This process is characterized amongst others by less naive T-cells and more senescent phenotypes, which have been implicated in the pathogenesis of many age-related diseases. Thus far, reports regarding the long-term adaptation effects of exercise on T-cell phenotypes are scant and largely equivocal. These inconsistencies may be due to potential contributors to immunosenescence, particularly cytomegalovirus infection, which is considered a hallmark of T-cell senescence. Therefore, we sought to investigate the impact of cytomegalovirus serostatus on the distribution of peripheral T-cell subsets following long-term exercise in older women. METHODS: One hundred women (aged 65 years and above) were randomized to 3 times/weekly training at either intensive strength training (3 × 10 repetitions at 80% of one-repetition maximum, n = 31), strength endurance training (2 × 30 repetitions at 40% of one-repetition maximum, n = 33), or control (passive stretching exercise, n = 36) for 6 weeks. All training sessions were supervised by trained instructors to minimize the risk of injury and to ensure that the participants adhered to the training protocol throughout the entire range of motion. The T-cell percentages and absolute blood counts were determined before and after 6 weeks (24 h-48 h after the last training session) using flow cytometry and a haematology analyser. Cytomegalovirus antibodies were measured in serum using Architect iSystem and cytomegalovirus serostatus was balanced in the three intervention groups. C-reactive protein was measured using immunonephelometry. RESULTS: We report for the first time that 6 weeks of strength endurance training significantly decreased senescence-prone T-cells along with a small increase in the number of CD8- naive T-cells in blood. The absolute counts of senescent-like T-cells decreased by 44% (from 26.03 ± 35.27 to 14.66 ± 21.36 cells/µL, p < 0.01) and by 51% (from 6.55 ± 12.37 to 3.18 ± 6.83 cells/µL, p < 0.05) for the CD8+ and CD8- T-cell pools, respectively. Intriguingly, these changes were observed in cytomegalovirus seropositive, but not cytomegalovirus seronegative individuals. CONCLUSIONS: In conclusion, the present study shows that strength endurance training leads to a reduction in circulating senescence-prone T-cells in cytomegalovirus seropositive older women. It remains to be established if monitoring of peripheral senescence-prone T-cells may have utility as cellular biomarkers of immunosenescence.

Effect of Antihypertensive and Statin Medication Use on Muscle Performance in Community-Dwelling Older Adults Performing Strength Training.

OBJECTIVES: Antihypertensive drugs (AHTD) and statins have been shown to have effects beyond their primarily designed purpose; here we investigate their possible effect on muscle performance and strength in older adults following a physical exercise programme. DESIGN: The Senior PRoject INtensive Training (SPRINT) study is a randomised, controlled clinical trial designed to evaluate the effects of physical exercise on the immune system and muscle performance in older adults. PARTICIPANTS: In this secondary analysis, we included 179 independent participants (aged 65 years and above). We applied further categorisation based on medication use: AHTD (including, angiotensin-converting enzyme inhibitors [ACEI], angiotensin II receptor blockers [ARB], ß-blockers, and other AHTD) and statins. INTERVENTION: Participants were allocated randomly to one of the three exercise protocols: intensive strength training 3 times/week (3 × 10 repetitions at 80% of one-repetition maximum), strength endurance training (2 × 30 repetitions at 40% of one-repetition maximum), or control (passive stretching exercise) for 6 weeks. MEASUREMENTS: The change in maximal hand grip strength (GS), muscle fatigue resistance (FR), Muscle Strength Index (MSI), the 6-min walk test (6MWT), and Timed Up and Go Test (TUG) were assessed before and after 6 weeks of training. RESULTS: After 6 weeks, muscle strength (MSI and TUG) improved significantly in all training groups compared to baseline, independently of AHTD use. Moreover, AHTD had no effect on exercise improvements, with no significant differences between medication groups, except for TUG in ARB users, which exhibited a significantly lower performance. On the other hand, statin users presented a significantly longer FR time, indicating better performance compared to non-users. Finally, medication did not affect the participants' commitment to the training programme. CONCLUSION: Our study showed that statins and ARB usage might affect participant's response to strength training. Nevertheless, 6 weeks of training significantly improved muscle strength and performance irrespective of AHTD or statin use.

Muscle fatigability measured with Pneumatic and Hydraulic handgrip systems are not interchangeable.

BACKGROUND: Fatigue resistance (FR) was here defined as the time during which grip strength (GS) drops to 50% of its maximum during sustained contraction. Since different GS systems exist, we compared FR obtained with Pneumatic (Pneu) and Hydraulic (Hydr) handgrip systems. Hand pain induced by both systems was also investigated since this might influence FR-outcomes. METHODS: 618 young controls (Y: reference group), 426 middle-aged (MA) and 234 old community-dwelling adults (OLD), and 50 hospitalized patients (HOSP) participated. FR was recorded with Pneu and Hydr. Grip work corrected for body weight (area under the strength-time curve; GWBW = 0.75 ∗ maximal GS ∗ FR / body weight) was calculated. We corrected for body weight since heavier or more obese participants will have to engage more strength and sustain the effort over time. Thereafter GWBW was expressed as T-scores representing the deviation from the mean score of the sex-specific reference group. Experienced pain, its intensity and whether pain hindered participants to sustain the contraction were questioned. RESULTS: Overall, although significant correlation between FR measured with both systems was found (r = 0.418, p < 0.001), FR measured by Pneu (55.7 ± 35.0 s) was higher compared to Hydr (34.2 ± 18.4 s). There was a proportional difference in FR measured with both systems (R2 = 0.36, p < 0.001), highlighting the longer participants could sustain FR test, the higher the difference in FR measured with both systems. Overall, there was no difference in pain variables between both systems. Independent of sex and system, GWBW deviated less from reference group in MA compared to OLD and HOSP. In OLD, GWBW deviated less from reference group than HOSP, independent of sex and system. CONCLUSION: Participants were unable to sustain the contraction with Hydr as long as with Pneu. Hydr seems less able to identify subjects with higher levels of muscle endurance. Based on the GWBM-scores we can conclude that either system can be used for assessing muscle fatigability, but Pneu may be more sensitive as differences can be detected more easily.

Strength Endurance Training but Not Intensive Strength Training Reduces Senescence-Prone T Cells in Peripheral Blood in Community-Dwelling Elderly Women.

Aging is characterized by a progressive decline in immune function known as immunosenescence. Although the causes of immunosenescence are likely to be multifactorial, an age-associated accumulation of senescent T cells and decreased naive T-cell repertoire are key contributors to the phenomenon. On the other hand, there is a growing consensus that physical exercise may improve immune response in aging. However, the optimum training modality required to obtain beneficial adaptations in older subjects is lacking. Therefore, we aimed to investigate the effects of exercise modality on T-cell phenotypes in older women. A total of 100 women (aged ≥ 65 years) were randomized to either intensive strength training (80% of one-repetition maximum ), strength endurance training (40% one-repetition maximum), or control (stretching exercise) for 2-3 times per week during 6 weeks. The T-cell percentages and absolute counts were determined using flow cytometry and a hematology analyzer. C-reactive protein was measured using immunonephelometry. We report for the first time that 6 weeks of strength endurance training significantly decreased the basal percentage and absolute counts of senescence-prone T cells, which was positively related to the number of training sessions performed. Conceivably, training protocols with many repetitions-at a sufficiently high external resistance-might assist the reduction of senescence-prone T cells in older women.

Martin Vigorimeter assesses muscle fatigability in older adults better than the Jamar Dynamometer.

INTRODUCTION: Muscle fatigability can be measured based on sustained handgrip performance, but different grip strength devices exist and their relationship to frailty remains unclear. We aimed to compare muscle fatigability obtained by Martin Vigorimeter and Jamar Dynamometer in older women across levels of frailty. METHOD: 53 community-dwelling women living in Greece (63-100 y), categorized according to tertiles on the Frailty Index score (FI) as: low-frail (FI < 0.19), intermediate-frail (FI 0.19-0.36), and high-frail (FI > 0.36). Fatigue resistance (FR, time for maximal grip strength to decrease to 50% during sustained contraction) was measured with both Martin Vigorimeter and Jamar Dynamometer, and grip work (GW, reflecting the area under the time-force curve) was calculated. RESULTS: FR, when measured with the Martin Vigorimeter, was approximately double in low-frail (44.3 ±â€¯24.6 s) compared to high-frail participants (23.9 ±â€¯12.7 s, p = 0.011), whereas FR was similar across frailty groups when measured with the Jamar Dynamometer. In logistic regression models, FR (OR = 0.94 [0.90-0.99]) and GW (OR = 0.90 [0.82-0.99]) were significantly related to high frailty when measured with the Martin Vigorimeter but not when measured with Jamar Dynamometer. There is a significantly proportional difference in FR measured with both devices (R2 = 0.364, p < 0.001), highlighting that the longer the participant could sustain the FR test, the higher the difference in FR measured with both devices. CONCLUSION: Our results suggest that the Martin Vigorimeter is a more appropriate handgrip device compared with the Jamar Dynamometer to assess muscle fatigability for older women across levels of frailty. When measured with the Martin Vigorimeter, high-frail participants show twice the level of fatigability compared to low-frail, whereas no difference was observed when using the Jamar Dynamometer. Older participants might stop the FR test prematurely when using the Jamar Dynamometer, before muscle fatigue is reached, indicating that the Jamar Dynamometer is unable to identify those participants with higher levels of muscle endurance. Martin Vigorimeter assessed muscle fatigability might be a good additional marker to include in frailty tools.