Minimal power required to ascend a flight of stairs versus actual power measured with body-fixed sensors in adults aged 19-85 years.

A good stair-climbing (SC) ability is crucial for independent living in older adults. A simple formula that estimates the mean power needed to ascend a flight of stairs in a predetermined time (i.e., total ascent duration) is easy to implement in practice, but lacks information on actual power values generated per step. The latter is possible with body-fixed sensors. This study aimed at comparing both methodologies and investigating their sensitivity to detect age-related differences. 318 participants (162 ♀; age 19-85 years) were tested on a 6-step staircase and two methodologies were used to estimate mean SC power: (1) a body-fixed sensor with automated detection of power production per step, and (2) a mathematic equation based on timed ascent duration, body mass and stair height. SC power was 210.4 W lower with formula compared to sensor, lower in women versus men and in older versus young adults (p < 0.001). The difference in SC power between sensor and formula was greater in individuals with better performance (i.e., men and young adults) (p < 0.001), indicating a ceiling effect of the formula in well-functioning and younger individuals. Likewise, ICC's between both methodologies showed poor reliability in people aged <65 years (0.087-0.363) and moderate to good reliability in people aged ≥65 years (0.453-0.780). To conclude, participants with better SC performance are able to largely overshoot the minimal power required to ascend the stairs in a certain duration. This makes the sensor more sensitive to identify early age-related differences compared to the formula.

Recreational Football Training Increases Leg-Extensor Velocity Production in 55- To 70-Year Old Adults: A Randomized Controlled Trial.

This study investigated the effects of 10 weeks of recreational football training on the leg-extensor force-velocity (F-V) profile in 55- to 70-year-old adults. Simultaneous effects on functional capacity, body composition and endurance exercise capacity were examined. Forty participants (age 63.5 ± 3.9 years; 36♂ 4♀) were randomized in a football training (FOOT, n = 20) and a control (CON, n = 20) group. FOOT performed 45-min to 1-h of football training sessions with small-sided games twice a week. Pre- and post-intervention assessments were performed. The results revealed a greater increase in maximal velocity (d = 0.62, pint = 0.043) in FOOT compared to CON. No interaction effects were found for maximal power and force (pint > 0.05). 10-m fast walk improved more (d = 1.39, pint < 0.001), 3-step stair ascent power (d = 0.73, pint = 0.053) and body fat percentage (d = 0.61, pint = 0.083) tended to improve more in FOOT than in CON. RPE and HR values at the highest speed level during a submaximal graded treadmill test decreased more in FOOT compared to CON (RPE: d = 0.96, pint = 0.005; HR: d = 1.07, pint = 0.004). Both the number of accelerations and decelerations as well as the distance spent in moderate- and high-speed zones increased markedly throughout the 10-week period (p < 0.05). Participants perceived the sessions as very enjoyable and feasible. In conclusion, recreational football training resulted in improved leg-extensor velocity production, which translated to a better performance on functional capacity tests that rely on a high execution velocity. Simultaneously, exercise tolerance was improved and body fat percentage tended to reduce. It appears that short-term recreational football training can induce broad-spectrum health benefits in 55- to 70-year-old adults with only 2 hours of training per week.

Reduced knee extensor torque production at low to moderate velocities in postmenopausal women with knee osteoarthritis.

This study aimed to determine deficits in knee extensor muscle function through the torque-time and torque-velocity relationships and whether these deficits are associated with reduced functional performance in postmenopausal women with knee osteoarthritis (KOA). A clinical sample of postmenopausal women with established KOA (n = 18, ≥55 years) was compared to an age-matched healthy control sample (CON) (n = 26). The deficits in different parameters of the knee extensor torque-time (maximal isometric torque and rate of torque development) and torque-velocity relationship (maximum muscle power, maximal velocity and torque at 0-500°·s-1 ) were assessed through a protocol consisting of isometric, isotonic and isokinetic tests. Functional performance was evaluated with sit-to-stand and stair-climbing tasks using a sensor-based technology (ie, time- and power-based outcomes). Postmenopausal women with KOA showed reduced maximal isometric torque (Hedge's g effect size (g) = 1.05, p = 0.001) and rate of torque development (g = 0.77-1.17, all p ≤ 0.02), combined with impaired torque production at slow to moderate velocities (g = 0.92-1.70, p ≤ 0.004), but not at high or maximal velocities (g = 0.16, p > 0.05). KOA were slower (g = 0.81-0.92, p ≤ 0.011) and less powerful (g = 1.11-1.29, p ≤ 0.001) during functional tasks. Additionally, knee extensor deficits were moderately associated with power deficits in stair climbing (r = 0.492-0.659). To conclude, knee extensor muscle weakness was presented in postmenopausal women with KOA, not only as limited maximal and rapid torque development during isometric contractions, but also dynamically at low to moderate velocities. These deficits were related to impaired functional performance. The assessment of knee extensor muscle weakness through the torque-time and torque-velocity relationships might enable individual targets for tailored exercise interventions in KOA.

Age-related differences in vastus lateralis fascicle behavior during fast accelerative leg-extension movements.

Leg-extensor rate of power development (RPD) decreases during aging. This study aimed to identify the underlying mechanism of the age-related decline in RPD during a fast acceleration in terms of in vivo vastus lateralis (VL) fascicle shortening behavior. Thirty-nine men aged between 25 and 69 years performed three maximal isokinetic leg-extensor tests with a fixed initial acceleration of 45° knee extension in 150 ms until 340°/s knee angular velocity. RPD, VL activity, and ultrasound images were recorded to assess (relative) fascicle shortening and mean shortening velocity for the phases of electromechanical delay, pretension, and acceleration. Our findings show that fascicle shortening and mean shortening velocity during a fast action increase with aging (0.002 per year, P = .035 and 0.005 s-1 per year, P = .097, respectively), mainly due to a higher amount of shortening in the phase of electromechanical delay. The ratio of VL fascicle length over upper leg length at rest showed a negative correlation (r = -.46, P = .004) with RPD/body mass, while pennation angle at rest showed a trend toward a positive correlation (r = .28, P = .089). To conclude, our findings indicate that the ability to reach high VL fascicle shortening velocities in vivo is not reduced in older men while performing preprogrammed fast accelerations. The greater amount of fascicle shortening in old age is probably the result of age-related differences in the tendinous properties of the muscle-tendon complex, forcing the fascicles to shorten more in order to transmit the muscle force to the segment.

Effect of acceleration on the rate of power development and neural activity of the leg extensors across the adult life span.

PURPOSE: The rate of power development (RPD) represents the capacity to rapidly generate power during a dynamic muscle contraction. As RPD is highly susceptible to aging, its decline can have important functional consequences. However, the effect of age on RPD in response to rapid changes in movement velocity (cfr. fall incidence) is not yet clear. Therefore, the present study aimed to examine the effect of age on RPD and neural drive in response to different accelerations. METHODS: Three maximal isokinetic leg extensor tests at 540°/s with different initial acceleration phases at 3200, 5700 and 7200°/s2 were performed. RPD, which is the slope of the power-time curve during the acceleration phase, was calculated for 83 subjects aged between 20 and 69 years. Mean electromyography signal amplitude was determined for rectus femoris (RF), vastus lateralis (VL) and biceps femoris muscles. RESULTS: The average annual age-related decline rate of RPD at highest acceleration was - 2.93% and was - 1.52% and - 1.82% higher compared to lower acceleration rates (p < 0.001). This deficit can probably be explained by an age-related impairment in neural drive during the first 75 ms of the acceleration phase, as evidenced by a reduced RF and VL neuromuscular activity of - 0.30% and - 0.36% at highest versus lowest acceleration (p < 0.05). CONCLUSION: These findings highlight the inability of aged individuals to quickly respond to abrupt changes in movement velocity, which requires more focus in training and prevention programs.

Differences in Maximum Voluntary Excitation Between Isometric and Dynamic Contractions are Age-Dependent.

Obtaining true maximum voluntary excitation appears to be more difficult in older populations than in young populations. The aims of this study were (1) to determine whether differences in maximum voluntary excitation obtained from maximum voluntary isometric contraction (MVIC) and (sub-)maximum voluntary dynamic contraction [(s-)MVDC] are age dependent, and (2) to determine how normalizing electromyographic signals to corresponding maximum voluntary excitations affects variance between participants and the likelihood of normalized signals exceeding 100%. MVIC, s-MVDC, and MVDC were recorded in 10 young women, and MVIC and s-MVDC were recorded in 19 older women. A significant age × contraction mode interaction effect was found for vastus lateralis (P = .04). In young women, MVDC elicited the highest maximum voluntary excitation for vastus lateralis and rectus femoris (P < .05). In older women, no differences in maximum voluntary excitation were found (P > .05). Normalization to dynamic contractions resulted in lower between-participant variance of electromyography amplitudes, though not for all muscles, and decreased the number of normalized signals exceeding 100% in young women. These findings indicate that differences in maximum voluntary excitation across contraction modes are age dependent. Therefore, one should be cautious when comparing normalized signals between age groups; however, overall dynamic contractions may be preferable over isometric contractions for normalization purposes.

Weight bearing exercise can elicit similar peak muscle activation as medium-high intensity resistance exercise in elderly women.

PURPOSE: To assess whether stepping-based weight bearing exercise (WBE) can elicit peak activation of upper leg muscles similar to resistance exercise (RE) at an intensity required to induce strength gains in elderly women. METHODS: Muscular activation of several upper leg muscles was measured during RE and WBE in a cohort of 19 healthy elderly women (69.3 ± 3.4 years). WBE consisted of forward and lateral stepping with step heights of 10, 20 and 30 cm. Muscular activation was compared to 60% of one-repetition maximum (1-RM) of congruent RE. RESULTS: Peak activation during WBE was higher than RE at 60% 1-RM during forward and lateral stepping in vastus lateralis starting at 20 cm (p = 0.049 and p = 0.001), and biceps femoris at 30 cm step height (p = 0.024 and p = 0.030). Gluteus maximus peak activation matched RE at 60% 1-RM at 20 and 30 cm step height regardless of step direction (p ≥ 0.077). Peak activation of the rectus femoris and gluteus medius matched RE activation at 60% 1-RM during lateral stepping at 30 cm (p = 0.355 and p = 0.243, respectively) but not during forward stepping. WBE did not induce similar activation as RE in the semitendinosus. CONCLUSION: In WBE, most upper leg muscles were recruited at an equal or higher intensity than in RE at 60% 1-RM. Lateral stepping at 30 cm step height showed the highest training potential of all WBE's applied.

Maximum Dynamic Lower-Limb Strength Was Maintained During 24-Week Reduced Training Frequency in Previously Sedentary Older Women.

Walker, S, Serrano, J, and Van Roie, E. Maximum dynamic lower-limb strength was maintained during 24-week reduced training frequency in previously sedentary older women. J Strength Cond Res 32(4): 1063-1071, 2018-There is little study into the effects of reducing strength training below the recommended twice weekly frequency, particularly in older women, despite the possibility that individuals will encounter periods of reduced training frequency. The purpose of the present study was to determine the effects of a period of reduced training frequency on maximum strength and muscle mass of the lower limbs in comparison with the recommended training frequency of twice per week. After an initial 12-week period, where all subjects trained twice per week, a reduced strength training group (RST) trained once per week, whereas another strength training group (ST) continued to train twice per week for 24 weeks. A nontraining age-matched control group (CON) was used for comparison. All subjects were tested for leg press 1-repetition maximum (1RM), electromyogram (EMG) amplitude of vastus lateralis and medialis, and quadriceps cross-sectional area (CSA) measured by panoramic ultrasound at weeks 0, 12, and 36. Both ST and RST continued to increase 1RM during the reduced training frequency period compared with control (∼8% and ∼5% vs. ∼-3%, respectively; p ≤ 0.05). Accompanying these changes were significant increases in EMG amplitude in both ST and RST (p ≤ 0.05). However, the initial gains in quadriceps CSA made from week 0 to week 12 in RST were lost when training once per week (RST ∼-5%). Therefore, reduced training frequency in this population does not adversely affect maximum strength or muscle activity but can negatively affect muscle mass, even reversing training-induced gains. Older individuals not training at least twice per week may compromise potential increases in muscle mass, important in counteracting effects of aging.

Effects of resistance training at different loads on inflammatory markers in young adults.

PURPOSE: Suppressing inflammaging at an early stage in life via exercise might prevent chronic diseases later in life. The aim was to investigate the influence of resistance training at different external loads on inflammatory markers in healthy young adults. METHODS: Serum was collected for basal levels of cytokines (IL-1beta, IL-6, IL-8, sTNFR1, IL-1RA, IL-10 and GM-CSF) before and after 9 weeks exercise from 36 young (22 ± 2 years) healthy subjects who were randomized to three times weekly supervised resistance training at either HImax (n = 12, 1 × 10-12 repetitions at 80% 1RM), LO (n = 12, 1 × 10-12 repetitions at 40% 1RM), or LOmax (n = 12, 1 × 10-12 repetitions at 40% 1RM preceded by 60 repetitions at 20-25% 1RM) respectively. RESULTS: Overall, IL-8 increased (p < 0.001) and IL-6 decreased (p = 0.001) after training, but no significant time*group interaction was found (respectively, p = 0.283 and p = 0.058 for IL-8 and IL-6). When analyzed separately, IL-8 increased significantly in HImax (p = 0.022) and LOmax (p = 0.024); and IL-6 decreased significantly in LOmax (p = 0.009) and LO (p = 0.013). No significant overall time effect was observed for sTNFR1 and IL-1RA; however, in HImax sTNFR1 (p = 0.031) and IL-1RA (p = 0.014) increased significantly, but remained unchanged in LOmax and LO. IL-1beta, IL-10 and GM-CSF levels remained undetectable in most participants. CONCLUSIONS: Nine weeks of resistance training-irrespective of the external load-have beneficial effects on circulating IL-8 and IL-6. In addition, training at high external load increases the anti-inflammatory cytokines sTNFR1 and IL-1RA. The results of this study show that resistance training has anti-inflammatory effects in healthy young persons and that the response of the different inflammatory mediators depends on the magnitude of the external load.

Low- and High-Resistance Exercise: Long-Term Adherence and Motivation among Older Adults.

BACKGROUND: In terms of motivation and long-term adherence, low-resistance exercise might be more suitable for older adults than high-resistance exercise. However, more data are needed to support this claim. OBJECTIVE: The objective was to investigate the effect of low- and high-resistance exercise protocols on long-term adherence and motivation. METHODS: This study was designed as an exploratory 24-week follow-up of a randomized 12-week resistance training intervention in older adults. Participants were free to decide whether or not they continued resistance training at their own expense following the intervention. Fifty-six older adults were randomly assigned to HIGH [2 × 10-15 repetitions at 80% of one repetition maximum (1RM)], LOW (1 × 80-100 repetitions at 20% of 1RM), or LOW+ (1 × 60 repetitions at 20% of 1RM + 1 × 10-20 repetitions at 40% 1RM). Motivation, self-efficacy and the perceived barriers for continuing resistance exercise were measured after cessation of each supervised intervention and at follow-up, while long-term adherence was probed retrospectively at follow-up. RESULTS: Participants reported high levels of self-determined motivation before, during, and after the supervised intervention, with no differences between groups (p > 0.05). Nevertheless, only few participants continued strength training after the intervention: 17% in HIGH, 21% in LOW+, and 11% in LOW (p > 0.05). The most commonly reported barriers for continuing resistance exercise were perceived lack of time (46%), being more interested in other physical activities (40%), seasonal reasons (40%), and financial cost (28%). CONCLUSION: The results suggest no difference in long-term adherence after the end of a supervised exercise intervention at high or low external resistances. Long-term adherence was limited despite high levels of self-determined motivation during the interventions. These findings highlight the importance of further research on developing strategies to overcome barriers of older adults to adhere to resistance exercise without supervision.

Older adults' lower-limb muscle power production throughout a full flight of stairs: Reliability and comparison between different stair models.

Lower-limb muscle power should be closely monitored to prevent age-related functional ability declines. Stair-climbing (SC) power is a functionally relevant measurement of lower-limb muscle power. Body-fixed sensors can measure power production throughout the different steps of a flight of stairs to assess different aspects of performance. This study investigated: 1) power production throughout a full flight of stairs; 2) if staircases with less or more steps can provide similar information; and 3) test-retest reliability of SC power. 116 community-dwelling older adults (57 women) ascended three staircases as fast as possible: 12, 6 and 3 steps. Mean vertical power production per step was collected and analyzed using a commercial body-fixed sensor and software. Three phases were found in SC power production: 1) an acceleration phase, i.e., the power produced in step 1 (P1); 2) a phase where the highest performance (Pmax) is reached and; 3) a fatiguing phase with power loss (Ploss; only measurable on 12-step staircase). Mean power (Pmean) over the different steps was also evaluated. P1 did not differ between staircases (all p>0.05), whereas Pmax and Pmean were higher with increasing number of steps (p = 0.073 -p<0.001). P1, Pmax and Pmean were strongly correlated between staircases (r = 0.71-0.95, p<0.05). and showed good to excellent reliability (ICC = 0.66-0.95, p<0.05). Ploss showed poor reliability. To conclude, measurements of SC power production (P1, Pmax and Pmean) with a single sensor on the lower back are reliable across different staircases. A small, transportable, 3-step staircase can be used for measuring power production in clinical practices with no access to regular staircases. However, absolute values are dependent on the number of steps, indicating that measurements to track performance changes over time should always be done using an identical stair model.

Free-Living Sit-to-Stand Characteristics as Predictors of Lower Extremity Functional Decline Among Older Adults.

PURPOSE: Habitual strength and power-demanding activities of daily life may support the maintenance of adequate lower-extremity functioning with ageing, but this has been sparingly explored. Hence, we examined whether the characteristics of free-living sit-to-stand (STS) transitions predict a decline in lower-extremity functioning over a 4-year follow-up. METHODS: 340 community-dwelling older adults (60% women, age 75, 80 or 85 years) participated in this prospective cohort study. At baseline, a thigh-worn accelerometer was used continuously (3-7 days) to monitor the number and intensity of free-living STS transitions. A decline in lower-extremity functioning was defined as a drop of ≥2 points in the Short Physical Performance Battery (SPPB) from baseline to follow-up. Maximal isometric knee-extension strength was measured in the laboratory. RESULTS: 85 participants (75% women) declined in SPPB over 4 years. After adjusting for age, sex, and baseline SPPB points, higher free-living peak STS angular velocity (odds ratio [OR] = 0.70; 95% confidence interval [CI] = 0.52-0.92, per 20 deg/s increase) protected against a future decline. When adjusting the model for maximal isometric knee-extension strength, the statistical significance was attenuated (OR = 0.72; 95% CI = 0.54-0.96, per 20 deg/s increase). CONCLUSIONS: Performing STS transitions at higher velocities in the free-living environment can prevent a future decline in lower-extremity function. This indicates that changes in daily STS behavior may be useful in the early identification of functional loss. Free-living peak STS angular velocity may be a factor underlying the longitudinal association of lower-extremity strength and performance.

Long-term impact of strength training on muscle strength characteristics in older adults.

OBJECTIVE: To evaluate the long-term preventive impact of strength training on muscle performance in older adults. DESIGN: A 7-year follow-up on a 1-year randomized controlled trial comparing the effects of combined resistance training and aerobic training and whole-body vibration training on muscle performance. SETTING: University training center. PARTICIPANTS: Men and women (N=83; control [CON] group, n=27; strength-training intervention [INT] group, n=56) between 60 and 80 years of age. INTERVENTIONS: The INT group exercised 3 times weekly during 1 year, performing a combined resistance training and aerobic training program or a whole-body vibration training program. The former training program was designed according to American College of Sports Medicine guidelines. The whole-body vibration training program included unloaded static and dynamic leg exercises on a vibration platform. The CON group did not participate in any training program. MAIN OUTCOME MEASURES: Static strength (STAT), dynamic strength at 60°/s (DYN60) and at 240°/s (DYN240), speed of movement at 20% (S20). RESULTS: From baseline to postintervention, muscle performance did not change in the CON group, except for S20 (+6.55%±2.88%, P<.001). One year of strength training increased (P≤.001) STAT (+11.46%±1.86%), DYN60 (+6.96%±1.65%), DYN240 (+9.25%±1.68%), and S20 (+7.73%±2.19%) in the INT group. Between baseline and follow-up, muscle performance decreased (P<.001) in both groups. However, STAT and DYN60 showed a significantly lower loss in the INT group (-8.65%±2.35% and -7.10%±2.38%, respectively) compared with the CON group (-16.47%±2.69% and -15.08%±2.27%, respectively). This positive impact might be due to the preservation of the training-induced gains, given the similar annual decline rates in both groups from postintervention to follow-up. Additionally, in trained participants, aging seems to impact velocity-dependent strength and power more compared with basic strength, as the total losses in DYN240 (CON, -15.93%±2.64%; INT, -11.39%±1.95%) and S20 (CON, -14.39%±2.10%; INT, -13.16%±1.72%) did not differ significantly between the groups. CONCLUSIONS: A 1-year strength-training intervention results in an improved muscle performance in older adults 7 years after their enrollment in the intervention. However, an extensive exercise program cannot attenuate the age-related decline once the intervention stops.

"Every step counts!": effects of a structured walking intervention in a community-based senior organization.

This study evaluated "Every Step Counts!"- a 10-wk, structured walking intervention in a community-based senior organization - on promoting physical activity participation, fitness, and well-being among older adults (age ≥ 55 yr). The intervention prescribed pedometer-defined walks in weekly walking schedules. These were fitness-tailored and structured in walking load (intensity/volume) according to the principles of training progression. This intervention was offered as a social activity at meeting points of a community-based senior organization. Twenty-nine meeting points (n = 432) constituted the intervention condition. Ten meeting points (n = 148) formed the wait-list control condition. Measurements were organized at intervention start (pretest) and end (posttest). Intention-to-treat linear mixed models showed small positive intervention effects on physical activity, fitness, and aspects of well-being. These results confirm the effectiveness of structured walking interventions with systematic training progression and underscore the value of community-based senior organizations as intervention settings for older adults.

Impact of external resistance and maximal effort on force-velocity characteristics of the knee extensors during strengthening exercise: a randomized controlled experiment.

It remains controversial whether maximal effort attained by high external resistance is required to optimize muscle adaptation to strengthening exercise. Here, we compared different training protocols reaching maximal effort with either high-resistance (HImax, 80% of 1-repetition maximum [1RM]) or low-resistance (LOmax, ≤40% 1RM). Thirty-six young volunteers were randomly assigned to 9 weeks of leg extension training at either HImax (1 set of 10-12 repetitions at 80% 1RM), LO (1 set of 10-12 repetitions at 40% 1RM, no maximal effort), or LOmax (1 set of 10-12 repetitions at 40% 1RM, preceded [no rest] by 60 repetitions at 20-25% 1RM). Knee extension 1RM was measured preintervention and postintervention and before the 7th, 13th, and 19th training sessions. Preintervention and postintervention, knee extensor static (PTstat) and dynamic (PTdyn) peak torque, maximal work (MW), and speed of movement at 20% (S20), 40% (S40), and 60% (S60) of PTstat were recorded with a Biodex dynamometer. All the groups showed a significant increase in 1RM, with a greater improvement in HImax from the 13th session on (p < 0.05). The HImax was the only group that significantly increased PTstat (+7.4 ± 8.1%, p = 0.01). The LOmax showed a significantly greater increase in S20 (+6.0 ± 3.2%), PTdyn (+9.8 ± 5.6%), and MW (+15.1 ± 10.6%) than both HImax and LO (p = 0.044 for S20, p = 0.030 for PTdyn, p = 0.025 for MW) and was the only group that increased in S40 (+7.7 ± 9.7%, p = 0.032). In conclusion, significant differences between HImax and LOmax on force-velocity characteristics of the knee extensors were found, although maximal effort was achieved in both training regimens. Thus, LOmax may not be considered as a replacement for HImax but rather as an alternative with different training-specific adaptations.

Ten-year longitudinal changes in muscle power, force, and velocity in young, middle-aged, and older adults.

BACKGROUND: Maximum muscle power (Pmax ) is a biomarker of physical performance in all ages. No longitudinal studies have assessed the effects of aging on Pmax obtained from the torque-velocity (T-V) relationship, which should be considered the 'gold standard'. This study evaluated the longitudinal changes in the T-V relationship and Pmax of the knee-extensor muscles in young, middle-aged, and older adults after 10 years of follow-up. METHODS: Four hundred eighty-nine subjects (311 men and 178 women; aged 19-68 years) were tested at baseline and after a 10-year follow-up. Anthropometric data, daily protein intake, physical activity level (PAL), and knee-extension muscle function (isometric, isokinetic, and isotonic) were evaluated. A novel hybrid equation combining a linear and a hyperbolic (Hill-type) region was used to obtain the T-V relationship and Pmax of the participants, who were grouped by sex and age (young: 20-40 years; middle-aged: 40-60 years; and old: ≥60 years). Linear mixed-effect models were used to assess effects of time, sex, and age on T-V parameters, Pmax , and body mass index (BMI). Additional analyses were performed to adjust for changes in daily protein intake and PAL. RESULTS: Pmax decreased in young men (-0.6% per year; P < 0.001), middle-aged men and women (-1.1% to -1.4% per year; P < 0.001), and older men and women (-2.2% to -2.4% per year; P ≤ 0.053). These changes were mainly related to decrements in torque at Pmax at early age and to decrements in both torque and velocity at Pmax at older age. BMI increased among young and middle-aged adults (0.2% to 0.5% per year; P < 0.001), which led to greater declines in relative Pmax in those groups. S/T0 , that is, the linear slope of the T-V relationship relative to maximal torque, exhibited a significant decline over time (-0.10%T0 ·rad·s-1 per year; P < 0.001), which was significant among middle-aged men and old men and women (all P < 0.05). Annual changes in PAL index were significantly associated to annual changes in Pmax (P = 0.017), so the overall decline in Pmax was slightly attenuated in the adjusted model (-5.26 vs. -5.05 W per year; both P < 0.001). CONCLUSIONS: Pmax decreased in young, middle-aged, and older adults after a 10-year follow-up. The early declines in Pmax seemed to coincide with declines in force, whereas the progressive decline at later age was associated with declines in both force and velocity. A progressively blunted ability to produce force, especially at moderate to high movement velocities, should be considered a specific hallmark of aging.

Sensor- and equation-based sit-to-stand power: The effect of age and functional limitations.

Estimating lower-limb muscle power during sit-to-stand (STS) tests is feasible for large-scale implementation. This study investigated 1) whether age, functional limitations and sex have an influence on the movement strategy and power production during STS; and 2) potential differences between STS power estimated with either a simple equation or a sensor. Five-repetition STS data of 649 subjects (♂352 ♀297) aged 19 to 93 years were included. Subjects were divided in different age groups and levels of functioning. A body-fixed sensor measured (sub)durations, trunk movement (flexion/extension) and STS muscle power (Psensor). Additionally, mean STS muscle power was calculated by a mathematic equation (Alcazar et al., 2018b)Results revealed that 1) older subjects and women showed greater trunk flexion before standing up than younger subjects and men, respectively (both p < 0.001); 2) well-functioning adults seemed to have the tendency to not extend the trunk fully during the sit-to-stand transition (mean difference extension - flexion range = -15.3° to -13.1°, p < 0.001); 3) mobility-limited older adults spent more time in the static sitting and standing positions than their well-functioning counterparts (all p < 0.001); 4) STS power decreased with age and was lower in women and in limited-functioning subjects compared to men and well-functioning subjects, respectively (p < 0.05); 5) Pformula was highly related to Psensor (ICC = 0.902, p < 0.001); and 6) Pformula demonstrated higher values than Psensor in well-functioning adults [mean difference = -0.31 W/kg and -0.22 W/kg for men and women, respectively (p < 0.001)], but not among limited-functioning older adults. To conclude, this study showed that age and functional limitations have an influence on the movement strategy during a 5-repetition STS test. Differences in movement strategy can affect the comparison between Pformula and Psensor. In well-functioning older adults, Pformula was slightly higher than Psensor, which might be related to an incomplete extension in the sit-to-stand transition.

Association of Sit-to-Stand Capacity and Free-Living Performance Using Thigh-Worn Accelerometers among 60- to 90-Yr-Old Adults.

PURPOSE: Five times sit-to-stand (STS) test is commonly used as a clinical assessment of lower-extremity functional ability, but its association with free-living performance has not been studied. Therefore, we investigated the association between laboratory-based STS capacity and free-living STS performance using accelerometry. The results were stratified according to age and functional ability groups. METHODS: This cross-sectional study included 497 participants (63% women) 60-90 yr old from three independent studies. A thigh-worn triaxial accelerometer was used to estimate angular velocity in maximal laboratory-based STS capacity and in free-living STS transitions over 3-7 d of continuous monitoring. Functional ability was assessed with short physical performance battery. RESULTS: Laboratory-based STS capacity was moderately associated with the free-living mean and maximal STS performance ( r = 0.52-0.65, P < 0.01). Angular velocity was lower in older compared with younger and in low- versus high-functioning groups, in both capacity and free-living STS variables (all P < 0.05). Overall, angular velocity was higher in capacity compared with free-living STS performance. The STS reserve (test capacity - free-living maximal performance) was larger in younger and in high-functioning groups compared with older and low-functioning groups (all P < 0.05). CONCLUSIONS: Laboratory-based STS capacity and free-living performance were found to be associated. However, capacity and performance are not interchangeable but rather provide complementary information. Older and low-functioning individuals seemed to perform free-living STS movements at a higher percentage of their maximal capacity compared with younger and high-functioning individuals. Therefore, we postulate that low capacity may limit free-living performance.

Updating 'Perceptions and opinions on the COVID-19 pandemic in Flanders, Belgium' with data of two additional waves of a longitudinal study.

Adding to longitudinal data of three waves that were presented in an original dataset on perceptions and behaviours regarding government measures, fear of getting ill, and media use during the COVID-19 pandemic in Flanders (Belgium), this article presents information on two additional waves that were collected at two key moments in the pandemic in the same region: in late August 2020 (W4; as infection rates increased again; N = 505) and in the middle of March 2021, exactly one year after the first data collection (W5; N = 408). In W4 and W5, new respondents were added to the longitudinal sample to strengthen cross-sectional analyses. Additional information on informal care and physical activity was also collected. These data may be of interest to researchers who wish to explore dynamics of fear and attitudes towards public health measures during this particularly challenging time.

Association Between Free-Living Sit-to-Stand Transition Characteristics, and Lower-Extremity Performance, Fear of Falling, and Stair Negotiation Difficulties Among Community-Dwelling 75 to 85-Year-Old Adults.

BACKGROUND: Good sit-to-stand (STS) performance is an important factor in maintaining functional independence. This study investigated whether free-living STS transition volume and intensity, assessed by a thigh-worn accelerometer, is associated with characteristics related to functional independence. METHODS: Free-living thigh-worn accelerometry was recorded continuously for 3-7 days in a population-based sample of 75-, 80-, and 85-year-old community-dwelling people (479 participants; women n = 287, men n = 192). The records were used to evaluate the number and intensity (angular velocity of the STS phase) of STS transitions. Associations with short physical performance battery (SPPB), 5-times-sit-to-stand test (5×STS), isometric knee extension force, self-reported fear of falls, and self-reported difficulty in negotiating stairs were also assessed. RESULTS: The number of STS transitions, mean and maximal angular velocity were lower in older age groups (p < .05). All variables were higher in men than in women (p < .001) and were positively associated with SPPB total points, knee extension force (r ranged from 0.18 to 0.39, all p < .001) and negatively associated with 5×STS (r = -0.13 - -0.24, all p < .05), lower extremity functional limitations (p < .01), fear of falls (p < .01), and stair negotiation difficulties (p < .01). CONCLUSIONS: Free-living STS characteristics were related to lower-extremity performance, lower extremity functional limitations, self-reported fear of falls, and stair negotiation difficulties, which can be a sensitive indicator of impending functional decline. Moreover, STS transitions may provide an indicator of adequacy of lower-limb muscle strength among older individuals.