Effects of aging and sex on voluntary activation and peak relaxation rate of human elbow flexors studied with motor cortical stimulation

Data are equivocal on whether voluntary activation is preserved or decreased in old compared to young adults. Further, data are scant on the effect of age on the rate of muscle relaxation when the muscle is contracting voluntarily. Assessment of both measures with transcranial magnetic stimulation (TMS) yields information which cannot be obtained with traditional peripheral nerve stimulation. Hence, voluntary activation and peak relaxation rate of the elbow flexors were assessed with TMS during repeated maximal efforts in 30 men and 28 women between the ages of 22–84 years. Voluntary activation was similar for the two sexes (P = 0.154) and was not affected by age in men (96.2 ± 2.7 %; P = 0.887) or women (95.1 ± 3.0 %; P = 0.546). Men had a significantly faster peak rate of relaxation than women in absolute units (−880.0 ± 223.2 vs. −360.2 ± 78.5 Nm/ s, respectively; P < 0.001) and when normalized to subject strength (−12.5 ± 2.1 vs. −8.7 ± 1.0 s⁻¹, respectively; P < 0.001). Absolute and normalized relaxation rates slowed with age in men (P = 0.002 and P = 0.006, respectively), but not women (P = 0.142 and P = 0.950, respectively). Across the age range studied, all subjects, regardless of age or sex, were able to achieve high voluntary activation scores for the elbow flexors (~95 %). In contrast, peak relaxation rate was markedly faster in men than women and slowed with age in men but not women. Normalization of relaxation rates to strength did not affect the influence of age or sex.     

Combined effects of body composition and ageing on joint torque,muscle activation and co-contraction in sedentary women

This study aimed to establish the interplay between body mass, adiposity, ageing and determinants of skeletal muscle strength. One hundred and two untrained healthy women categorised by age into young (Y) (mean ± SD, 26.7 ± 9.4 years) vs. old (O) (65.1 ± 7.2 years) were assessed for body fat, lean mass, plantar flexion and dorsiflexion maximum voluntary isometric contraction (MVC) torque, muscle activation capacity and antagonist muscle co-contraction. MVC torque normalised to body mass in the obese group was 35 and 29 % lower (p < 0.05) in Y and 34 and 31 % lower (p < 0.05) in O, compared with underweight and normal weight individuals, respectively. Y with ≥40 % body fat had significantly lower activation than Y with <40 % body fat (88.3 vs. 94.4 %, p < 0.05), but O did not exhibit this effect. Co-contraction was affected by ageing (16.1 % in O vs. 13.8 % in Y, p < 0.05) but not body composition. There were significant associations between markers of body composition, age, strength and activation capacity, with the strongest correlation between muscle strength and total body mass (r² = 0.508 in Y, p < 0.001, vs. r² = 0.204 in O, p < 0.01). Furthermore, the age-related loss in plantar flexion (PF) MVC torque was exacerbated in obese compared to underweight, normal weight and overweight individuals (−0.96 vs. −0.54, −0.57 and −0.57 % per year, p < 0.05). The negative impact of adiposity on muscle performance is associated with not only muscular but also neural factors. Overall, the effects of ageing and obesity on this system are somewhat cumulative.     

Echo intensity is negatively associated with functional capacity in older women

Muscle quality is an important component of the functional profile of the elderly, and previous studies have shown that both muscle quantity and quality independently contribute to muscle strength of the elderly. This study aimed to verify the association between quadriceps femoris muscle quality, analyzed by specific tension and echo intensity (EI), and rate of torque development (RTD) of the knee extensor muscles with the functional performance in elderly active women. Forty-five healthy, active elderly women (70.28 ± 6.2) volunteered to participate in this study. Quadriceps femoris muscle thickness and EI were determined by ultrasonography. Knee extension isometric peak torque and RTD were obtained from maximal isometric voluntary contraction curves. The 30-s sit-to-stand-up (30SS) test and usual gait speed (UGS) test were applied to evaluate functional performance. Rectus femoris EI presented a significant negative correlation with 30SS (r = −0.505, P < 0.01), UGS (r_s = −0.347, P < 0.05), and isometric peak torque (r = −0.314, P < 0.05). The quadriceps femoris EI correlated negatively with 30SS (r = −0.493, P < 0.01) and isometric peak torque (r = −0.409, P < 0.01). The EI of the quadriceps femoris and all quadriceps muscle portions significantly correlated with RTD. RTD significantly correlated with physical performance in both functional tests (30SS = r = 0.340, P < 0.05; UGS = r_s = 0.371, P < 0.05). We concluded that muscle EI may be an important predictor of functional performance and knee extensor power capacity in elderly, active women.     

Acute exercise increases resistance to oxidative stress in young but not older adults

A single bout of acute exercise increases oxidative stress and stimulates a transient increase in antioxidant enzymes. We asked whether this response would induce protection from a subsequent oxidative challenge, different from that of exercise, and whether the effects were affected by aging. We compared young (20 ± 1 years, n = 8) and older (58 ± 6 years, n = 9) healthy men and women. Resistance to oxidative stress was measured by the F₂-isoprostane response to forearm ischemia/reperfusion (I/R) trial. Each participant underwent the I/R trial twice, in random order; once after performing 45 min of cycling on the preceding day (IRX) and a control trial without any physical activity (IRC). Baseline F₂-isoprostane levels were significantly lower at IRX compared to IRC (P < 0.05) and not different between groups. F₂-isoprostane response to IRX was significantly lower compared to IRC in young (P < 0.05) but not different in the older group. Superoxide dismutase activity in response to acute exercise was significantly higher in young compared to older adults (P < 0.05). These data suggest that signal transduction of acute exercise may be impaired with aging. Repeated bouts of transient reactive oxygen species production as seen with regular exercise may be needed to increase resistance to oxidative stress in older individuals.     

Short-term strength training improves muscle quality and functional capacity of elderly women

To assess effects of a short-term strength training (ST) program on muscle quality (MQ) and functional capacity, 36 sedentary elderly women (age = 66.0 ± 8 year, height = 159.1 ± 9.2 cm, body mass = 68.3 ± 12.1 kg, body fat = 37.0 ± 4.2 %) were randomly divided into an experimental group (EG; n = 19) or a control group (CG; n = 17). The EG performed two to three sets of 12–15 repeats of leg press, knee extension, and knee flexion exercises, 2 days/week for 6 weeks. Before and after training, lower body one repetition maximum (1RM), functional performance tests, quadriceps femoris muscle thickness (MT), and muscle quality (MQ) (1RM and quadriceps MT quotient) were assessed. After training, only the EG showed significant improvements in 1RM (p < 0.05), 30-s sit-to-stand (p < 0.001), and 8 foot up-and-go (p < 0.001). In addition, only in the EG, significant increases in all quadriceps femoris MT measurements (vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris) (p ≤ 0.05), and MQ (p < 0.001) were demonstrated. No changes were observed in the CG. Furthermore, there were significant associations between individual changes in MQ and corresponding changes in 30-s sit-to-stand (r = 0.62, p < 0.001), and 8 foot up-and-go (r = −0.71, p < 0.001). In conclusion, a ST program of only 6 weeks was sufficient to enhance MQ of the knee extensors in elderly women, which resulted in beneficial changes in functional capacity.     

Aging blunts hyperventilation-induced hypocapnia and reduction in cerebral blood flow velocity during maximal exercise

Cerebral blood flow (CBF) increases from rest to ∼60% of peak oxygen uptake (VO_2peak) and thereafter decreases towards baseline due to hyperventilation-induced hypocapnia and subsequent cerebral vasoconstriction. It is unknown what happens to CBF in older adults (OA), who experience a decline in CBF at rest coupled with a blunted ventilatory response during VO_2peak. In 14 OA (71 ± 10 year) and 21 young controls (YA; 23 ± 4 years), we hypothesized that OA would experience less hyperventilation-induced cerebral vasoconstriction and therefore an attenuated reduction in CBF at VO_2peak. Incremental exercise was performed on a cycle ergometer, whilst bilateral middle cerebral artery blood flow velocity (MCA V_mean; transcranial Doppler ultrasound), heart rate (HR; ECG) and end-tidal PCO₂ (P_ETCO₂) were monitored continuously. Blood pressure (BP) was monitored intermittently. From rest to 50% of VO_2peak, despite greater elevations in BP in OA, the change in MCA V_mean was greater in YA compared to OA (28% vs. 15%, respectively; P < 0.0005). In the YA, at intensities >70% of VO_2peak, the hyperventilation-induced declines in both P_ETCO₂ (14 mmHg (YA) vs. 4 mmHg (OA); P < 0.05) and MCA V_mean (−21% (YA) vs. −7% (OA); P < 0.0005) were greater in YA compared to OA. Our findings show (1), from rest-to-mild intensity exercise (50% VO_2peak), elevations in CBF are reduced in OA and (2) age-related declines in hyperventilation during maximal exercise result in less hypocapnic-induced cerebral vasoconstriction.     

Elite triathletes in ‘Ironman Hawaii’ get older but faster

The age of peak performance has been well investigated for elite athletes in endurance events such as marathon running, but not for ultra-endurance (>6 h) events such as an Ironman triathlon covering 3.8 km swimming, 180 km cycling and 42 km running. The aim of this study was to analyze the changes in the age and performances of the annual top ten women and men at the Ironman World Championship the ‘Ironman Hawaii’ from 1983 to 2012. Age and performances of the annual top ten women and men in overall race time and in each split discipline were analyzed. The age of the annual top ten finishers increased over time from 26 ± 5 to 35 ± 5 years (r² = 0.35, P < 0.01) for women and from 27 ± 2 to 34 ± 3 years (r² = 0.28, P < 0.01) for men. Overall race time of the annual top ten finishers decreased across years from 671 ± 16 to 566 ± 8 min (r² = 0.44, P < 0.01) for women and from 583 ± 24 to 509 ± 6 min (r² = 0.41, P < 0.01) for men. To conclude, the age of annual top ten female and male triathletes in the ‘Ironman Hawaii’ increased over the last three decades while their performances improved. These findings suggest that the maturity of elite long-distance triathletes has changed during this period and raises the question of the upper limits of the age of peak performance in elite ultra-endurance performance.     

Effect of resistance training with different frequencies and detraining on muscular strength and oxidative stress biomarkers in older women

The aim of this study was to compare the effect of resistance training (RT) performed with different frequencies followed by a detraining period on muscular strength and oxidative stress (OS) biomarkers in older women. Twenty-seven physically independent women (68.8 ± 4.8 years, 69.1 ± 14.3 kg, 156.0 ± 6.5 cm, and 28.3 ± 4.9 to kg.m⁻²) were randomly assigned to perform a RT program for 2 or 3 days per week (G2X = 13 vs. G3X = 14) for 12 weeks followed by 12 weeks of detraining period. One repetition maximum (1RM) tests were used as measures of muscular strength (three exercises, three attempts for each exercise, 3–5 min of rest between attempts, and 5 min of rest between exercises). Advanced oxidized protein products (AOPP) and total radical-trapping antioxidant parameter (TRAP) were used as oxidative stress indicators. Both groups increased muscular strength after 12 weeks of training (P < 0.05) in chest press (G2X = +11.9 % vs. G3X = +27.5 %, P < 0.05), knee extension (G2X = +18.4 % vs. G3X = +16.7 %, P > 0.05), and preacher curl (G2X = +37.6 % vs. G3X = +36.7 %, P > 0.05). On the other hand, 12 weeks of detraining were not sufficient to eliminate the major effects produced by RT on muscular strength, although a significant decrease (P < 0.05) has been observed for chest press (G3X = −9.1 % vs. G2X = −10.2 %, P > 0.05), knee extension (G2X = −14.9 % vs. G3X = −12.1 %, P > 0.05), and preacher curl (G2X = −20.5 % vs. G3X = −17.4 %, P > 0.05). Pre- to post-training, both groups showed significant (P < 0.05) increases in TRAP (G2X = +6.9 % vs. G3X = +15.1 %) with no statistical significant difference between the groups (P > 0.05), and the scores remained elevated compared to pre-training after 12 weeks of detraining. AOPP was not changed by RT or detraining (P > 0.05). The results suggest that a 12-week RT program with a frequency of 2 days per week may be sufficient to improve muscular strength and OS in older women and detraining for 12 weeks does not completely reverse the changes induced by RT.     

The effectiveness of aerobic exercise for hypertensive population: A systematic review and meta‐analysis

The study aims to evaluate the effectiveness of different durations of aerobic exercise on hypertensive patients. Four electronic databases (PubMed, Embase, Cochrane Library, and Web of Science) were searched from their inception until July 2018. English publications and randomized controlled trials involving aerobic exercise treatment for hypertensive population were included. Two reviewers independently extracted the data. The Cochrane''s Risk of Bias tool was used to assess the quality of included studies. In this systematic review, a total of 14 articles were included, involving 860 participants. The quality of the included studies ranged from moderate to high. The results of the meta‐analysis showed that compared with the control group, significant effects of aerobic exercise were observed on reducing systolic blood pressure (SBP) (mean difference [MD] = −12.26 mm Hg, 95% confidence interval [CI] = −15.17 to −9.34, P < 0.05), diastolic blood pressure (DBP; MD = −6.12 mm Hg, 95% CI = −7.76 to −4.48, P < 0.05), and heart rate (MD = −4.96 bpm, 95% CI = −6.46 to −3.43, P < 0.05). In addition, significant reductions were observed in ambulatory DBP (MD = −4.90 mm Hg, 95% CI = −8.55 to −1.25, P < 0.05) and ambulatory SBP (MD = −8.77mm Hg, 95% CI = −13.97 to −3.57, P < 0.05). Therefore, aerobic exercise might be an effective treatment for blood pressure improvement in hypertensive patients. However, the effectiveness between the duration of different treatment needs to be well‐designed and rigorous studies will be required to verify the dataset.     

Thermoregulation and fluid balance during a 30-km march in 60- versus 80-year-old subjects

The presence of impaired thermoregulatory and fluid balance responses to exercise in older individuals is well established. To improve our understanding on thermoregulation and fluid balance during exercise in older individuals, we compared thermoregulatory and fluid balance responses between sexagenarians and octogenarians during prolonged exercise. Forty sexagenarians (60 ± 1 year) and 36 octogenarians (81 ± 2 year) volunteered to participate in a 30-km march at a self-selected pace. Intestinal temperature (T_in) and heart rate were recorded every 5 km. Subjects reported fluid intake, while urine output was measured and sweat rate was calculated. Octogenarians demonstrated a lower baseline T_in and a larger exercise-induced increase in T_in compared to sexagenarians (1.2 ± 0.5 °C versus 0.7 ± 0.4 °C, p < 0.01), while maximum T_in tended to be higher in octogenarians (38.4 ± 0.4 °C versus 38.2 ± 0.3 °C, p = 0.09). Exercise intensity (70 ± 11 % versus 70 ± 9 %) and exercise duration (7 h 45 min ± 0 h 57 min versus 7 h 24 min ± 0 h 58 min) were not different between octogenarians and sexagenarians. Octogenarians demonstrated lower fluid intake (251 ± 97 mL/h versus 325 ± 125 mL/h, p = 0.01) and urine output (28 ± 22 mL/h versus 52 ± 40 mL/h, p < 0.01) compared to sexagenarians. Furthermore, the sweat rate tended to be lower (294 ± 150 mL/h versus 364 ± 148 mL/h, p = 0.07) in the octogenarian group. Sodium levels and plasma volume changes were not different between sexagenarians and octogenarians (all p > 0.05). These results suggest that thermoregulatory responses deteriorate with advancing age, while fluid balance is regulated appropriately during a 30-km walking march under moderate ambient conditions.     

Effects of acute bouts of endurance exercise on retinal vessel diameters are age and intensity dependent

Alterations of retinal vessel diameters are associated with increased cardiovascular risk. We aimed to investigate changes in retinal vessel diameters in response to acute dynamic exercise of different intensities and whether these changes are age dependent. Seventeen healthy seniors (median (IQR) age 68 (65, 69) years) and 15 healthy young adults (median (IQR) age 26 (25, 28) years) first performed a maximal treadmill test (MTT) followed by a submaximal treadmill test (SMTT) and a resting control condition in randomised order. Central retinal arteriolar (CRAE) and central retinal venular (CRVE) diameter equivalents were measured before as well as 5 (t₅) and 40 (t₄₀) minutes after exercise cessation using a static retinal vessel analyser. Both exercise intensities induced a significant dilatation in CRAE and CRVE at t₅ compared to the control condition (P < 0.001). At t₄₀, the mean increase in CRAE and CRVE was greater for MTT compared to that for SMTT (CRAE 1.7 μm (95 % confidence interval (CI) −0.1, 3.6; P = 0.061); CRVE 2.2 μm (95 % CI 0.4, 4.1; P = 0.019)). However, the estimated difference at t₅ between seniors and young adults in their response to MTT compared to SMTT was 5.3 μm (95 % CI 2.0, 8.5; P = 0.002) for CRAE and 4.1 μm (95 % CI −0.4, 8.6; P = 0.076) for CRVE. Wider arteries and veins after maximal versus submaximal exercise for seniors compared to young adults suggest that myogenic vasoconstriction in response to exhaustive exercise may be reduced in seniors. Age-related loss of vascular reactivity has clinical implications since the arteriolar vasoconstriction protects the retinal capillary bed from intraluminal pressure peaks.

Electronic supplementary material

The online version of this article (doi:10.1007/s11357-014-9650-3) contains supplementary material, which is available to authorized users.     

Relationship between vitamin D and inflammatory markers in older individuals

In older persons, vitamin D insufficiency and a subclinical chronic inflammatory status frequently coexist. Vitamin D has immune-modulatory and in vitro anti-inflammatory properties. However, there is inconclusive evidence about the anti-inflammatory role of vitamin D in older subjects. Thus, we investigated the hypothesis of an inverse relationship between 25-hydroxyvitamin D (25(OH)D) and inflammatory markers in a population-based study of older individuals. After excluding participants with high-sensitivity C-reactive protein (hsCRP) ≥ 10 mg/dl and those who were on chronic anti-inflammatory treatment, we evaluated 867 older adults ≥65 years from the InCHIANTI Study. Participants had complete data on serum concentrations of 25(OH)D, hsCRP, tumor necrosis factor (TNF)-α, soluble TNF-α receptors 1 and 2, interleukin (IL)-1β, IL-1 receptor antagonist, IL-10, IL-18, IL-6, and soluble IL-6 receptors (sIL6r and sgp130). Two general linear models were fit (model 1—adjusted for age, sex, and parathyroid hormone (PTH); model 2—including covariates of model 1 plus dietary and smoking habits, physical activity, ADL disability, season, osteoporosis, depressive status, and comorbidities). The mean age was 75.1 ± 17.1 years ± SD. In model 1, log(25OH-D) was significantly and inversely associated with log(IL-6) (β ± SE = −0.11 ± 0.03, p = <0.0001) and log (hsCRP) (β ± SE = −0.04 ± 0.02, p = 0.04) and positively associated with log(sIL6r) (β ± SE = 0.11 ± 0.04, p = 0.003) but not with other inflammatory markers. In model 2, log (25OH-D) remained negatively associated with log (IL-6) (β ± SE = −0.10 ± 0.03, p = 0.0001) and positively associated with log(sIL6r) (β ± SE = 0.11 ± 0.03, p = 0.004) but not with log(hsCRP) (β ± SE = −0.01 ± 0.03, p = 0.07). 25(OH)D is independently and inversely associated with IL-6 and positively with sIL6r, suggesting a potential anti-inflammatory role for vitamin D in older individuals.     

Effect of age on in vivo oxidative capacity in two locomotory muscles of the leg

To determine the effects of age and sex on in vivo mitochondrial function of distinct locomotory muscles, the tibialis anterior (TA) and medial gastrocnemius (MG), of young (Y; 24 ± 3 years) and older (O; 69 ± 4) men (M) and women (W) of similar overall physical activity (PA) was compared. In vivo mitochondrial function was measured using phosphorus magnetic resonance spectroscopy, and PA and physical function were measured in all subjects. Overall PA was similar among the groups, although O (n = 17) had fewer daily minutes of moderate-to-vigorous PA (p = 0.001), and slowed physical function (p < 0.05 for all variables), compared with Y (n = 17). In TA, oxidative capacity (V_max; mM s⁻¹) was higher in O than Y (p < 0.001; Y = 0.90 ± 0.12; O = 1.12 ± 0.18). There was no effect of age in MG (p = 0.5; Y = 0.91 ± 0.17; O = 0.96 ± 0.24), but women had higher oxidative capacity than men (p = 0.007; M = 0.84 ± 0.18; W = 1.03 ± 0.18). In vivo mitochondrial function was preserved in healthy O men and women, despite lower intensity PA and physical function in this group. The extent to which compensatory changes in gait may be responsible for this preservation warrants further investigation. Furthermore, women had higher oxidative capacity in the MG, but not the TA.     

The skeletal muscle satellite cell response to a single bout of resistance-type exercise is delayed with aging in men

Skeletal muscle satellite cells (SCs) have been shown to be instrumental in the muscle adaptive response to exercise. The present study determines age-related differences in SC content and activation status following a single bout of exercise. Ten young (22 ± 1 years) and 10 elderly (73 ± 1 years) men performed a single bout of resistance-type exercise. Muscle biopsies were collected before and 12, 24, 48, and 72 h after exercise. SC content and activation status were assessed in type I and type II muscle fibers by immunohistochemistry. Myostatin and MyoD protein and messenger RNA (mRNA) expression were determined by Western blotting and rtPCR, respectively. In response to exercise, it took 48 h (young) and 72 h (elderly) for type II muscle fiber SC content to exceed baseline values (P < 0.01). The number of myostatin + SC in type I and II muscle fibers was significantly reduced after 12, 24, and 48 h of post-exercise recovery in both groups (P < 0.01), with a greater reduction observed at 24 and 48 h in the young compared with that in the elderly men (P < 0.01). In conclusion, the increase in type II muscle fiber SC content during post-exercise recovery is delayed with aging and is accompanied by a blunted SC activation response.     

Longitudinal impact of aging on muscle quality in middle-aged men

The present follow-up study aims at assessing the longitudinal changes in muscle quality after an interval of 9.45 years in middle-aged men. In addition, the relative contribution of muscle mass, muscle strength, and muscle power at middle age to these changes was investigated. The results showed a small, though unexpected, increase in total body and leg muscle mass (respectively 0.22 ± 0.04 and 0.29 ± 0.06 % yearly, p < 0.0001), whereas basic strength (−0.71 to −0.87 % yearly, p < 0.0001) and velocity-dependent strength and power (−1.19 to −1.86 % yearly, p < 0.0001) declined. Consequently, muscle quality, defined as the ratio of basic strength or velocity-dependent strength and power to muscle mass decreased (−1.46 to −2.43 % yearly, p < 0.0001) from baseline to follow-up. We found that baseline basic strength is a strong determinant of the decline in muscle quality basic strength with advancing age, whereas only a small part of the age-associated decline in muscle quality based on velocity-dependent strength and power could be explained. To conclude, our results indicate that muscle becomes less efficient at middle age and that baseline muscle strength is a strong predictor of this change. These findings imply that unmeasured neural factors, influencing both contraction speed and the capacity of muscle to produce strength, are possibly other involved determinants. Therefore, timely interventions including strength training and higher-velocity strength training at middle age are recommended.     

Thigh muscle volume in relation to age, sex and femur volume

Secular changes and intra-individual differences in body shape and size can confound cross-sectional studies of muscle ageing. Normalising muscle mass to height squared is often suggested as a solution for this. We hypothesised that normalisation of muscle volume to femur volume may be a better way of determining the extent of muscle lost with ageing (sarcopenia). Thigh and femur muscle volumes were measured from serial magnetic resonance imaging sections in 20 recreationally active young men (mean age 22.4 years), 25 older men (72.3 years), 18 young women (22.1 years) and 28 older women (72.0 years). There were no age-related differences in femur volume. The relationship between thigh muscle volume and femur volume (R² = 0.76; exponent of 1.12; P < 0.01) was stronger than that with height (R² = 0.49; exponent of 3.86; P < 0.01) in young participants. For young subjects, the mean muscle/bone ratios were 16.0 and 14.6 for men and women, respectively. For older men and women, the mean ratios were 11.6 and 11.5, respectively. The Z score for the thigh muscle/bone volume ratio relative to young subjects was −2.2 ± 0.7 for older men and −1.4 ± 0.8 for older women. The extent of sarcopenia judged by the muscle/bone ratio was approximately twice that determined when normalising to height squared. These data suggest that the muscle/bone ratio captures the intra-individual loss of muscle mass during ageing, and that the age-related loss of muscle mass may be underestimated when normalised to height squared. The quadriceps seems relatively more affected by ageing than other thigh muscles.     

Acute effects of passive stretching of the plantarflexor muscles on neuromuscular function: the influence of age

The acute effects of stretching on peak force (F_peak), percent voluntary activation (%VA), electromyographic (EMG) amplitude, maximum range of motion (MROM), peak passive torque, the passive resistance to stretch, and the percentage of ROM at EMG onset (%EMGonset) were examined in 18 young and 19 old men. Participants performed a MROM assessment and a maximal voluntary contraction of the plantarflexors before and immediately after 20 min of passive stretching. F_peak (−11 %), %VA (−6 %), and MG EMG amplitude (−9 %) decreased after stretching in the young, but not the old (P > 0.05). Changes in F_peak were related to reductions in all muscle activation variables (r = 0.56–0.75), but unrelated to changes in the passive resistance to stretch (P ≥ 0.24). Both groups experienced increases in MROM and peak passive torque and decreases in the passive resistance to stretch. However, the old men experienced greater changes in MROM (P < 0.001) and passive resistance (P = 0.02–0.06). Changes in MROM were correlated to increases in peak passive torque (r = 0.717), and the old men also experienced a nonsignificant greater (P = 0.08) increase in peak passive torque. %EMGonset did not change from pre- to post-stretching for both groups (P = 0.213), but occurred earlier in the old (P = 0.06). The stretching-induced impairments in strength and activation in the young but not the old men may suggest that the neural impairments following stretching are gamma-loop-mediated. In addition, the augmented changes in MROM and passive torque and the lack of change in %EMGonset for the old men may be a result of age-related changes in muscle-tendon behavior.     

Rudimentary signs of immunosenescence in Cytomegalovirus-seropositive healthy young adults

Ageing is associated with a decline in immune competence termed immunosenescence. In the elderly, this process results in an accumulation of differentiated ‘effector’ phenotype memory T cells, predominantly driven by Cytomegalovirus (CMV) infection. Here, we asked whether CMV also drives immunity towards a senescent profile in healthy young adults. One hundred and fifty-eight individuals (mean ± SD; age 21 ± 3 years, body mass index 22.7 ± 2.7 kg m²) were assessed for CMV serostatus, the numbers/proportions of CD4⁺ and CD8⁺ late differentiated/effector memory cells (i.e. CD27⁻CD28⁻/CD45RA⁺), plasma interleukin-6 (IL-6) and antibody responses to an in vivo antigen challenge (half-dose influenza vaccine). Thirty percent (48/158) of participants were CMV⁺. A higher lymphocyte and CD8⁺ count (both p < 0.01) and a lower CD4/CD8 ratio (p < 0.03) were observed in CMV⁺ people. Eight percent (4/58) of CMV⁺ individuals exhibited a CD4/CD8 ratio <1.0, whereas no CMV⁻ donor showed an inverted ratio (p < 0.001). The numbers of CD4⁺ and CD8⁺CD27⁻CD28⁻/CD45RA⁺ cells were ~ fourfold higher in CMV⁺ people (p < 0.001). Plasma IL-6 was higher in CMV⁺ donors (p < 0.05) and showed a positive association with the numbers of CD8⁺CD28⁻ cells (p < 0.03). Finally, there was a significant negative correlation between vaccine-induced antibody responses to the A/Brisbane influenza strain and CMV-specific immunoglobulin G titres (p < 0.05). This reduced vaccination response was associated with greater numbers of total CD8⁺ and CD4⁺ and CD8⁺CD27⁻CD28⁻/CD45RA⁺ cells (p < 0.05). This study observed marked changes in the immune profile of young adults infected with CMV, suggesting that this virus may underlie rudimentary aspects of immunosenescence even in a chronologically young population.     

Hormonal determinants and effect of ER22/23EK glucocorticoid receptor gene polymorphism on health status deterioration in the participants of the Mataró Ageing Study

The purpose of this study is to assess the potential relationships of circulating IGF-I, adrenal and gonadal steroids, and polymorphism ER22/23EK of the glucocorticoid receptor (GC-R) gene with nutritional, functional and cognitive deterioration in a group of elderly people living independently. This is a population-based prospective study with 313 individuals (160 women and 153 men, 76.7 ± 7 years) who participated. A physical exam, evaluation of functional capacity (Barthel scale), cognitive function (mini-mental state examination-MMSE), geriatric depression scale (GDS), mininutritional assessment (MNA-SF) and cardiometabolic status were performed at basal time point and at 2 years of follow-up. Biological measurements included cortisol, dehydroepiandrosterone (DHEA), DHEA sulphate, testosterone, estradiol, IGF-I and polymorphism ER22/23EK of the GC-R gene. Estradiol was associated with MNA-SF decrease over time (p < 0.01, adjusted for age and gender, beta = −0.17, p = 0.03). Weight loss was related to testosterone in men (8.6 vs 12.1 pg/ml in no losers; p = 0.03), and in women with GDS (13.0% with depression vs 3.3% with no depression; p = 0.05) and MMSE (22.2% with cognitive deterioration vs 4.8% with no cognitive deterioration; p = 0.049). Barthel decrease was associated with testosterone (p = 0.02, after adjusting for age and gender, beta = −0.520, p < 0.001), and SHBG (p < 0.01, adjusted for age and gender, beta = 0.18, p < 0.01). DHEA was associated with deterioration in the MMSE (p = 0.01, after adjusting for age, gender, GDS scale and academic status, beta = −0.26, p = 0.01). Frailty development was related only in men with testosterone levels at the beginning of the study (p = 0.017). ER22/23EK was found in 3% of the subjects and carriers had a lower prevalence of hypertension. Adrenal and gonadal steroids are associated to impairment of the ageing health condition in elderly individuals living independently in Spain. ER22/23EK polymorphism of the GC-R gene has a low prevalence in our population.     

Influence of exercise intensity on training-induced tendon mechanical properties changes in older individuals

This study compared the effects of low vs. high intensity training on tendon properties in an elderly population. Participants were pair-matched (gender, habitual physical activity, anthropometrics, and baseline knee extension strength) and then randomly assigned to low (LowR, i.e., ~40 % 1RM) or high (High R, i.e., ~80 % 1RM) intensity resistance training programmes for 12 weeks, 3× per week (LowR, n = 9, age 74 ± 5 years; HighR, n = 8, age 68 ± 6 years). Patellar tendon properties (stiffness [K], Young’s modulus [YM], cross-sectional area [T_CSA], and tendon length [T_L]) were measured pre and post training using a combination of magnetic resonance imaging (MRI), B-mode ultrasonography, dynamometry, electromyography and ramped isometric knee extensions. With training K showed no significant change in the LowR group while it incremented by 57.7 % in the HighR group (p < 0.05). The 51.1 % group difference was significant (p < 0.05). These differences were still apparent when the data was normalized for T_CSA and T_L, i.e., significant increase in YM post-intervention in HighR (p < 0.05), but no change in LowR. These findings suggest that when prescribing exercise for a mixed genders elderly population, exercise intensities of ≤40 % 1RM may not be sufficient to affect tendon properties.