Giuseppe De Vito

Muscle strength, power and adaptations to resistance training in older people

Muscle strength and, to a greater extent, power inexorably decline with ageing. Quantitative loss of muscle mass, referred to as “sarcopenia”, is the most important factor underlying this phenomenon. However, qualitative changes of muscle fibres and tendons, such as selective atrophy of fast-twitch fibres and reduced tendon stiffness, and neural changes, such as lower activation of the agonist muscles and higher coactivation of the antagonist muscles, also account for the age-related decline in muscle function. The selective atrophy of fast-twitch fibres has been ascribed to the progressive loss of motoneurons in the spinal cord with initial denervation of fast-twitch fibres, which is often accompanied by reinnervation of these fibres by axonal sprouting from adjacent slow-twitch motor units (MUs). In addition, single fibres of older muscles containing myosin heavy chains of both type I and II show lower tension and shortening velocity with respect to the fibres of young muscles. Changes in central activation capacity are still controversial. At the peripheral level, the rate of decline in parameters of the surface-electromyogram power spectrum and in the action-potential conduction velocity has been shown to be lower in older muscle. Therefore, the older muscle seems to be more resistant to isometric fatigue (fatigue-paradox), which can be ascribed to the selective atrophy of fast-twitch fibres, slowing in the contractile properties and lower MU firing rates. Finally, specific training programmes can dramatically improve the muscle strength, power and functional abilities of older individuals, which will be examined in the second part of this review.

Contractile muscle volume and agonist-antagonist coactivation account for differences in torque between young and older women

It is controversial whether specific tension (the ratio between muscle strength and size) declines with aging. Therefore, contractile muscle volume was estimated separately from the intramuscular noncontractile tissue by magnetic resonance imaging, and maximum isometric torque was measured in the knee extensors and flexors of 10 young (22.8 ± 5.7 years) and 10 older (69.5 ± 2.4 years) healthy active women. Specific tension was lower in the older women both in the extensors (93.1 ± 20.1 kN·m−2 vs. 112.1 ± 12.3 kN·m−2; P < 0.05) and in the flexors (100 ± 31 kN·m−2 vs. 142.7 ± 23.9 kN·m−2; P < 0.01). This was accompanied by an increase in the percentage coactivation of the knee flexors during knee extension. These data suggest that the lower level of muscle torque in the older women can be explained not only by smaller contractile muscle mass but also by increased coactivation of the antagonist muscles during knee extension.

Enhancing cognitive functioning in the elderly: multicomponent vs resistance training

Purpose The primary purpose of this study was to compare the effects of two different exercise training programs on executive cognitive functions and functional mobility in older adults. A secondary purpose was to explore the potential mediators of training effects on executive function and functional mobility with particular reference to physical fitness gains. Methods A sample of 42 healthy community dwelling adults aged 65 to 75 years participated twice weekly for 3 months in either: (1) multicomponent training, prioritizing neuromuscular coordination, balance, agility, and cognitive executive control; or (2) progressive resistance training for strength conditioning. Participants were tested at baseline (T1), following a 4-week control period (T2), and finally at postintervention (T3) for executive function (inhibition and cognitive flexibility) and functional mobility (maximal walking speed with and without additional task requirements). Cardiorespiratory and muscular fitness were also assessed as potential mediators. Results Indices of inhibition, the functions involved in the deliberate withholding of prepotent or automatic responses, and measures of functional mobility improved after the intervention, independent of training type. Mediation analysis suggested that different mechanisms underlie the effects of multicomponent and progressive resistance training. While multicomponent training seemed to directly affect inhibitory capacity, resistance training seemed to affect it indirectly through gains in muscular strength. Physical fitness and executive function variables did not mediate functional mobility changes. Conclusion These results confirm that physical training benefits executive function and suggest that different training types might lead to such benefits through different pathways. Both types of training also promoted functional mobility in older adulthood; however, neither inhibitory capacity, nor muscular strength gains seemed to explain functional mobility outcomes.

The effectiveness of two novel techniques in establishing the mechanical and contractile responses of biceps femoris

Portable tensiomyography (TMG) and myotonometry (MMT) devices have been developed to measure mechanical and contractile properties of skeletal muscle. The aim of this study was to explore the sensitivity of the aforementioned techniques in detecting a change in passive mechanical properties of the biceps femoris (BF) muscle as a result of change in knee joint angle (i.e. muscle length). BF responses were assessed in 16 young participants (23.4 ± 4.9 years), at three knee joint angles (0°, 45° and 90°), for maximal isometric torque (MIT) along with myo-electrical activity. Contractile and mechanical properties were measured in a relaxed state. Inter-day reliability of the TMG and MMT was also assessed. MIT changed significantly (p < 0.01) across the three angles, so did stiffness and other parameters measured with MMT (p < 0.01). Conversely, TMG could detect changes only at two knee angles (0° and 45°, p < 0.01), when there is enough tension in the muscle. Reliability was overall insufficient for TMG whilst absolute reliability was excellent (coefficient of variation < 5%) for MMT. The ability of MMT more than TMG to detect an inherent change in stiffness can be conceivably exploited in a number of clinical/therapeutic applications that have to do with unnatural changes in passive muscle stiffness.

Differences between young and older women in maximal force, force fluctuations, and surface emg during isometric knee extension and elbow flexion

The loss of muscle strength with aging appears to be greater in the lower than upper limbs, but strength and its neural control have never been compared in the same population of individuals in both upper and lower limbs. The aim of this study was to investigate differences between eight young (20–31 years) and eight older (68–76 years) healthy women in maximal voluntary contraction (MVC), force fluctuations, median frequency (MDF) of the surface electromyogram (sEMG), and muscle fiber conduction velocity (MFCV) during sustained isometric elbow flexion (EF) and knee extension (KE), performed at moderate to high force intensity. Older women showed larger fluctuations of force with endurance and changes in sEMG pointing to less fatigue, especially at high level of force, with no differences between upper and lower extremities. This may have significant implications in the design of rehabilitation programs directed to this population. Muscle Nerve, 2004

Divergence of intracellular and extracellular HSP72 in type 2 diabetes: does fat matter?

Mammalian cells have developed a range of adaptations to survive against acute and prolonged (but not lethal) stresses (Beckmann et al. 1992). Among these adaptations, the heat shock response is the most conserved, being found in all prokaryotes and eukaryotes (Locke and Noble 1995). Heat shock proteins (HSPs) are considered part of a family of proteins known as “stress proteins” since their expression is induced by a wide range of stressors, such as oxidative stress (Krause et al. 2007), thermal stress (Yang et al. 1996), ischaemia (Richard et al. 1996), exercise (Krause et al. 2007), metabolic stress (Beckmann et al. 1992) and many others. The genes encoding Hsps are highly conserved, and many of these genes and their protein products can be assigned to different families on the basis of their typical molecular weight (kDa): HSP110 (or officially named HSPH), HSP90 (or HSPC), HSP70 (or HSPA), HSP60 (or HSPD1), HSP40 (or DNAJ) and small hsp families (HSPB) (Kampinga et al. 2009). In eukaryotes, many families comprise multiple members that differ in inducibility, intracellular localization and function (Feder and Hofmann 1999). HSP72 (or HSPA1A) is the inducible and the most abundant of all HSPs, accounting for 1–2% of cellular protein and being rapidly induced during cell stress (Noble et al. 2008), especially in the skeletal muscle cells (Madden et al. 2008). As molecular chaperones, the intracellular HSP70 protein (iHSP72) can interact with other proteins (unfolded, in non-native state and/or stress-denatured conformations) to avoid inappropriate interactions, formation of protein aggregates and degradation of damaged proteins, as well as helping the correct refolding of proteins (Madden et al. 2008). Other HSP functions include protein translocation (Chirico et al. 1988), anti-apoptosis (Garrido et al. 2001) and anti-inflammatory responses (Homem de Bittencourt et al. 2007). The anti-inflammatory role of the iHSP72 is mediated by its interaction with the proteins involved in the activation of the nuclear factor κ-B (NF-κB), blocking its translocation to the nucleus and inducing the cessation of the inflammatory process (Homem de Bittencourt et al. 2007; Silveira et al. 2007). More recently, the HSP roles have been expanded to include control of cell signalling (Calderwood et al. 2007), modulation of immune response (Johnson and Fleshner 2006) and for chronic diseases conditions (Kampinga et al. 2007), such as diabetes, control of obesity and insulin resistance (Chung et al. 2008; Krause and Rodrigues-Krause Jda 2011). Recent data has indicated that a lack of iHSP72 response to stress can be linked to the levels of insulin resistance in skeletal muscle cells (Chung et al. 2008; Kurucz et al. 2002). Patients with T2DM have been shown to have reduced iHSP72 gene expression, which has been correlated with reduced insulin sensitivity (Kurucz et al. 2002). Furthermore, earlier studies in patients with T2DM reported that hot tub therapy improved glycaemic control (Bernstein 2000; Bathaie et al. 2010; Hooper 1999), additionally showing an inverse correlation between iHSP72 messenger RNA (mRNA) expression and the degree of T2DM (Kurucz et al. 2002). The underlying mechanisms behind the lower induction of iHSP72 expression in diabetic patients is not fully understood, but appears to be connected to the activation of proteins involved on inflammatory response (and sensitive to changes in redox state), such as the c-jun amino terminal kinase (JNK), the inhibitor of IκB (IKK), the tumor necrosis factor alpha (TNF-α) and nuclear factor kappa b (NF-κB) (Chung et al. 2008). Activation of these proteins appears to inhibit the major inductor of HSP72, the heat shock factor 1 (HSF-1), leading to a low iHSP72 expression and induction of the stress response (Chung et al. 2008). Currently, several HSP-inducing drugs are under investigation or in clinical trials for diabetic neuropathy, neurodegenerative diseases (Westerheide and Morimoto 2005; Kurthy et al. 2002) and for the prevention of insulin resistance and treatment of impaired glycaemic control (Kurucz et al. 2002; Gupte et al. 2009a; Literati-Nagy et al. 2009; Vitai et al. 2009; Kavanagh et al. 2009). Considering that skeletal muscle is the major tissue responsible for whole body insulin-mediated glucose uptake, disturbances in skeletal muscle, such as oxidative stress and inflammatory processes, can easily progress to insulin resistance and diabetes (Newsholme et al. 2009). Physical exercise is a known inducer of glucose uptake and is also a substantial inductor of iHSP72 expression (Krause et al. 2007). This may explain, in part, the beneficial effects of exercise in diabetic patients. Therefore, strategies to increase skeletal muscle iHSP72 expression (or over-expression) could result in improved glycaemic control, reduced insulin resistance and avoidance of T2DM. Heat shock proteins were long thought to be exclusive cytoplasmic proteins with functions restricted to the intracellular compartment. However, an increasing number of observations have shown that they may be released into the extracellular space (eHSP72) and have a wide variety of effects on other cells (Tytell 2005). The eHSP72 function is in general associated with the activation of the immune system (Whitham and Fortes 2008). For example, eHSP72 has been reported as an inductor of neutrophils microbicidal capacity (Ortega et al. 2006) and chemotaxis (Ortega et al. 2009), recruitment of NK (natural killer) cells (Horn et al. 2007) as well as cytokine production in immune cells (Asea et al. 2000; Johnson and Fleshner 2006). Besides that, eHSP72 was recently shown to be involved in the inducement of neural cell protection under stress conditions (Krause and Rodrigues-Krause Jda 2011). In addition, hyperglycaemia is known to be involved in inflammation and vascular complications associated with diabetes, arising from reactive oxygen species generation and action (Wei et al. 2009; Wright et al. 2006). As oxidative stress is a powerful inductor of iHSP72 (Krause et al. 2007), it is expected that during inflammatory and oxidative stress states in diabetes, the levels of these proteins in the extracellular medium (plasma and serum) may be higher in diabetic than non-diabetic participants. Indeed, type 1 (Oglesbee et al. 2005) and T2DM patients have higher levels of eHSP72, and this response has been related to the duration of the disease (Nakhjavani et al. 2010). In addition, serum eHSP72 concentrations are positively correlated with markers of inflammation, such as C-reactive proteins, monocyte count, and TNF-α (Mayer and Bukau 2005; Njemini et al. 2004). In summary, while intracellular levels of iHSP72 are decreased in T2DM and correlated with insulin resistance, extracellular eHSP72 levels are increased and correlated with oxidative damage and stress. To date, no study has investigated both intracellular and extracellular levels of HSP72 in T2DM patients simultaneously. Herein, we aimed to determine the levels of HSP72, intracellularly (skeletal muscle) and extracellularly (blood plasma) in three groups of patients: obese without T2DM and obese with T2DM and non-obese with T2DM. We also determined HSF-1 skeletal muscle expression for all groups.

Effects of aldosterone receptor blockade in patients with mild-moderate heart failure taking a beta-blocker

Spironolactone improves prognosis in severe heart failure (HF). We investigated its effects in patients with mild–moderate HF treated with an ACE inhibitor and beta‐blocker.

Physiological responses to fitness activities: a comparison between land-based and water aerobics exercise.

This study compared the heart rate (HR) and blood lactate (BL) responses in young healthy women performing the same routine of aerobics exercise in 3 different conditions: on land, in shallow water (0.8 m), and in deep water (1.4 m). The average age and body mass index (BMI) of the group were 27.4 years and 22.6 kg·m−2, respectively. The highest HR and BL values were reached during land aerobics (median HR values were 138.0 and 161.5 b·min−1, and lactate values were 3.10 and 5.65 mmol·L−1 at slow and at faster pace, respectively). These parameters were progressively reduced going from shallow water (121.5 and 154.0 b·min−1, 1.75 and 3.15 mmol·L−1) to deep water (97.5 and 113.5 b·min−1, 1.70 and 1.75 mmol·L−1). The HR measured as percentage of maximum HR varied from 48.43% to 77.53% depending on the water depth and the pace. These data indicate that exercise in water significantly reduces HR and BL production compared with the same exercise performed on land.

Anthropometric and strength variables to predict freestyle performance times in elite master swimmers

Zampagni, ML, Casino, D, Benelli, P, Visani, A, Marcacci, M, and De Vito, G. Anthropometric and strength variables to predict freestyle performance times in elite master swimmers. J Strength Cond Res 22: 1298-1307, 2008-The aims of this study were to determine in elite master swimmers of both genders whether, using anthropometric variables and the hand grip strength measure, it was possible to predict freestyle performance time, whether the considered predictors were related similarly to different events (50, 100, 200, 400, 800 m), and whether they were the same in male and female master swimmers. The relationships between performance times and age, body mass, height, arm length, forearm length, forearm muscle volume, and hand grip strength were examined in 135 elite master swimmers. Pearsons simple correlation coefficients were calculated and then prediction equations were developed. Age, height, and hand grip strength were the best predictors in short-distance events, whereas only age and height were predictors in middle- and long-distance events. The corresponding coefficient of determination (R2) of performance times were 0.84 in the 50-m event, 0.73 in the 100-m event, 0.75 in the 200-m event, 0.66 in the 400-m event, and 0.63 in the 800-m event. These regression equations were then cross-validated in a control group of 126 nonelite, age-matched swimmers, obtaining significant and good correlations for all distances (range, r = 0.67 and 0.83; p < 0.01), indicating that predictors are valid in an extended sample of master swimmers. Differences between sexes were not found in 50-m event, but were present in all other events. These models might be useful to determine individual performance times by contributing to improving the individuals training program and the selection of master swimmers. Coaches could have better accuracy in determining whether an athlete needs a strength training program in order to optimize performance time.

Effects of age and limb dominance on upper and lower limb muscle function in healthy males and females aged 40–80 years

Abstract This study investigated the effects of gender, age, and dominance on upper and lower limb muscle function. One hundred and fifty-two males and females aged 20–30 and 40–80 years were recruited. Maximal voluntary isometric strength (MVC) and rate of force development (RFD) of the knee extensor muscles, and handgrip MVC were measured bilaterally as indicators of lower and upper limb muscle function, respectively. In both sexes, significant main effects were found for age (knee extension MVC, RFD, and handgrip MVC) and limb dominance (handgrip MVC). Men exhibited a steeper age-related decline in muscle function than women, particularly in the lower limb [dominant limb: knee extension MVC −56% (men) vs. −35% (women); handgrip MVC −30% (men) vs. −26% (women); RFD −67% (men) vs. −47% (women); non-dominant limb: knee extension MVC −49% (men) vs. −36% (women); handgrip MVC −26% (men) vs. −24% (women); RFD −62% (men) vs. −44% (women)]. Although men showed a higher rate of decline in muscle function, in absolute terms they demonstrated better muscle function than women in all age groups, which has important implications for independence and quality of life. A clear asymmetry in muscle function was evident in both sexes only for handgrip MVC.