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Frailty is increasingly recognized as a geriatric syndrome that shares common biomedical determinants with rapid muscle fatigue: aging, disease, inflammation, physical inactivity, malnutrition, hormone deficiencies, subjective fatigue, and changes in neuromuscular function and structure. In addition, there is an established relationship between muscle fatigue and core elements of the cycle of frailty as proposed by Fried and colleagues (sarcopenia, neuroendocrine dysregulation and immunologic dysfunction, muscle weakness, subjective fatigue, reduced physical activity, low gait speed, and weight loss). These relationships suggest that frailty and muscle fatigue are closely related and that low tolerance for muscular work may be an indicator of frailty phenotype.
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... Natural adult aging is associated with decreased neuromuscular fatigue resistance, evidenced by a decrease in neuromuscular power/strength, across a variety of physical activity levels (Dalton et al., 2010;Sundberg, Kuplic, et al., 2018;Theou et al., 2008) and muscle groups (Dalton et al., 2015(Dalton et al., , 2010Senefeld et al., 2017;Sundberg, Kuplic, et al., 2018;Wallace et al., 2016) compared with young adults. This fatiguability is amplified when neuromuscular fatigue resistance is evaluated using muscle power, not strength, as the criterion measure. ...
... This fatiguability is amplified when neuromuscular fatigue resistance is evaluated using muscle power, not strength, as the criterion measure. This age-related decreased fatigue resistance has negative implications on activities of daily living, such as standing balance and walking (Senefeld et al., 2017), and is associated with frailty (Theou et al., 2008). Therefore, understanding the neuromuscular determinants of fatigue resistance of aged muscles assessed via power, especially the knee extensors (KE), is essential to identify ways to improve and maintain a high quality of life for older adults. ...
... Frailty and sarcopenia are linked conditions associated to musculoskeletal aging (Allen et al., 2021;Gandolfini et al., 2019). Frailty has an association with neuromuscular fatigue resistance (Theou et al., 2008), and sarcopenia includes the decline in maximal muscle power (Franchi et al., 2019). Therefore, it is important for older adults to improve both neuromuscular fatigue resistance and maximal power output. ...
Article
This study investigated associations of fatigue resistance determined by an exercise-induced decrease in neuromuscular power with prefatigue neuromuscular strength and power of the knee extensors in 31 older men (65-88 years). A fatigue task consisted of 50 consecutive maximal effort isotonic knee extensions (resistance: 20% of prefatigue isometric maximal voluntary contraction torque) over a 70° range of motion. The average of the peak power values calculated from the 46th to 50th contractions during the fatigue task was normalized to the prefatigue peak power value, which was defined as neuromuscular fatigue resistance. Neuromuscular fatigue resistance was negatively associated with prefatigue maximal power output (r = -.530) but not with prefatigue maximal voluntary contraction torque (r = -.252). This result highlights a trade-off between prefatigue maximal power output and neuromuscular fatigue resistance, implying that an improvement in maximal power output might have a negative impact on neuromuscular fatigue resistance.
... This sensation of tiredness may indeed characterize frailty by reflecting depletion of physiological reserve capacity. Even so, muscle fatigability, a reduced tolerance for muscular work may be also an important indicator of frailty (Theou et al., 2008;Zengarini et al., 2015). Remarkably, none of the frailty tools reported in the literature include a direct assessment of muscle fatigability. ...
... There are several reasons to hypothesize a physiologically based association between frailty and muscle fatigability since they share common biomedical determinants (Theou et al., 2008). In addition, the key elements of the vicious cycle of frailty, as proposed by Fried and colleagues (Fried et al., 2004), include both physiological determinants (sarcopenia, neuroendocrine dysregulation and immunological dysfunction) and clinical markers of frailty (muscle weakness, subjective fatigue, reduced physical activity, low gait speed and weight loss) (Theou et al., 2008). ...
... There are several reasons to hypothesize a physiologically based association between frailty and muscle fatigability since they share common biomedical determinants (Theou et al., 2008). In addition, the key elements of the vicious cycle of frailty, as proposed by Fried and colleagues (Fried et al., 2004), include both physiological determinants (sarcopenia, neuroendocrine dysregulation and immunological dysfunction) and clinical markers of frailty (muscle weakness, subjective fatigue, reduced physical activity, low gait speed and weight loss) (Theou et al., 2008). Interestingly, the group of Westerblad et al. showed that muscle fatigue occurs before the onset of muscle weakness in a mouse model of premature ageing (Yamada et al., 2012). ...
Article
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 ± 24.6 s) compared to high-frail participants (23.9 ± 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.
... Broadly speaking, fatigue can be divided into self-perceived feeling of fatigue (including sleep problems, depressive feelings, tiredness and performance-based feeling of tiredness) and resistance to physical tiredness which include a fatigue assessment such as muscle fatigue. Theou et al. (2008) showed in an explorative study that muscle fatigue and frailty share the same biomedical determinants (ea. ...
... In contrast, sedentary behaviour stimulates biopsychosocial processes that increase the feeling of fatigue (Avlund, 2010). Research also showed that protein intake has the potential to decrease muscle fatigue by creating more muscle mass, strength and functionality (Theou et al., 2008). Finally, an important process associated to the pathogenesis of fatigue and frailty is inflammation. ...
Article
Purpose: To identify the different fatigue items in existing frailty scales. Methods: PubMed, Web of Knowledge and PsycINFO were systematically screened for frailty scales. 133 articles were included, describing 158 frailty scales. Fatigue items were extracted and categorized in 4 fatigue constructs: "mood state related tiredness", "general feeling of tiredness", "activity based feeling of tiredness" and "resistance to physical tiredness". Results: 120 fatigue items were identified, of which 100 belonged to the construct "general feeling of tiredness" and only 9 to the construct "resistance to physical tiredness". 49,4% of the frailty scales included at least 1 fatiue item, representing 15 ± 9,3% of all items in these scales. Fatigue items have a significantly higher weight in single domain (dominantly physical frailty scales) versus multi domain frailty scales (21 ± 3.2 versus 10.6 ± 9.8%, p=<0,05 ). Conclusion: Fatigue is prominently represented in frailty scales, covering a great diversity in fatigue constructs and underlying pathophysiological mechanisms by which fatigue relates to frailty. Although fatigue items were more prevalent and had a higher weight in physical frailty scales, the operationalization of fatigue leaned more towards psychological constructs. This review can be used as a reference for choosing a suitable frailty scale depending on the type of fatigue of interest.
... Toutefois, dans ce genre d'évaluation, il est important de prendre en considération la fatigue musculaire. Ce paramètre devrait être pris en compte dans le diagnostic de la sarcopénie [152,188]. En effet, la fatigue musculaire, c'est-à-dire la capacité d'un muscle à produire une force soutenue sur une durée prolongée semble être un indicateur complémentaire de la force musculaire. Seule, l'étude de Bautmans et al. [152,188] s'est intéressée à la corrélation entre fatigue, résistance, force et la masse musculaire. ...
... En effet, la fatigue musculaire, c'est-à-dire la capacité d'un muscle à produire une force soutenue sur une durée prolongée semble être un indicateur complémentaire de la force musculaire. Seule, l'étude de Bautmans et al. [152,188] s'est intéressée à la corrélation entre fatigue, résistance, force et la masse musculaire. Même, si la force et la fatigue sont fortement corrélées à la masse musculaire, une masse musculaire identique peut, d'un sujet à l'autre, produire des niveaux très variables de force. ...
Thesis
Notre objectif à court terme est d’établir des courbes de référence Française de la densité osseuse (DMO) et de la composition corporelle masculine une fois que nous aurons toutes les données issues de tous les centres. Nous avons donc réalisé deux études préliminaires dans le cadre de ce projet dont les objectifs sont les suivants :A) Etudier les déterminants de la DMO corps entier mais aussi spécifiques de site osseux en lien avec les mesures de composition corporelle, de force musculaire et de l’activité physique chez l’homme jeune B) Cross-calibration in vitro des paramètres de densité osseuse et de composition corporelle mesurés par l’absorptiométrie bi-photonique à rayons X (DXA) afin d’établir les facteurs correctifs à appliquer in vivo dans le cadre de notre projet de courbe de référence chez l’homme jeune.Grâce à la DXA, notre étude a confirmé que la masse maigre était le facteur le plus important associé aux paramètres de la DMO sur tous les sites osseux étudiés et que la masse grasse avait un impact négatif sur la DMO. Aucune association n'a été trouvée entre activité physique et DMO. La force de préhension était significativement mais modérément corrélée avec la DMO. Concernant la cross-calibration, les résultats ont montré que l’oscillation des résultats entre les différents DXA des centres est un sujet de préoccupation pour les études multicentriques et en particulier pour l’évaluation de la composition corporelle. La cross-calibration nous a permis de calculer les facteurs correctifs à appliquer sur les données issues des centres impliqués. Afin de limiter ces variations, il serait souhaitable de mettre au point un fantôme corps entier standard qui serait utilisé pour les études multicentriques.
... Another concept of fatigue is muscle fatigue, which is defined as a decline in the maximum force-generating capacity of the muscle and its failure to maintain the required force as a result of muscle activity (Theou et al., 2008). A previous systematic review supported evidence that fatigue of the lower extremity and trunk muscles has a negative impact on balance and the performance of functional tasks in older adults, predisposing them to potential falls (Helbostad et al., 2010). ...
Article
Aim The aim of the present review was to examine the evidence of the relationship between self-reported or perceived fatigue and falls among older adults. Methods A systematic review, following the PRISMA recommendations, was performed. PubMed, Scopus, Web of Science, and Cinahl were searched from February 2021 until March 2021, without any limitation on publication date. The methodological quality of the recruited studies was assessed with the Newcastle-Ottawa scale. Results Of the 2,296 initially retrieved records, 20 met the inclusion criteria; 11 cohort and 9 cross-sectional studies. They were classified as “good or very good” studies. Data on 59,852 older adults was reported. Most studies reported a strong association between fatigue and incidence or risk of falls, with odds ratios ranging from 1.04 to 3.53. Evidence obout the relationship between fatigue and recurrent, as well as injurious, falls is limited. Conclusions Self-reported or perceived fatigue is associated with the incidence of falls or risk of falling among older adults. Nurses could contribute to decreasing the inicdence of falls through prevention and proper geriatric assessment, including the management of fatigue in their daily clinical practice. The evidence about the potential effect of fatigue on falls-related injuries is inconclusive and on recurrent falls remains to be further defined.
... Various studies suggest that sarcopenia is greater in frail older people than in non-frail older people [38]. Given that sarcopenia, like frailty syndrome, involves the dysfunction of different interrelated physiological systems, it is conceivable that the mechanisms leading to sarcopenia often overlap with those of frailty syndrome [52]. Chronic systemic inflammation has been implicated in the development of both frailty and sarcopenia, and several inflammatory mediators have been suggested as contributors to both sarcopenia and frailty [27,53,54]. ...
Article
Full-text available
Frailty is a geriatric syndrome characterized by a decrease in physiological reserve and reduced resistance to stress, as a result of an accumulation of multiple deficits in physiological systems. Frailty increases the vulnerability to adverse events and is associated with the aging process. Several studies show an association between frailty syndrome and altered blood lymphocyte levels, which is therefore potentially useful for monitoring interventions to improve or delay frailty. The main objective of this review is to provide an analysis of the current evidence related to changes in lymphocyte counts and their associations with frailty syndrome. To that end, the literature published in this field until March 2021 was in several databases: PubMed, SCOPUS, and Cochrane. Eighteen studies analyzed the association between lymphocyte counts, lymphocyte subtypes, and frailty syndrome. Eighteen studies were analyzed, and most of them reported associations. Interestingly, the association between frailty syndrome and lower lymphocytes counts appears in different clinical conditions. Further studies are needed to determine the sensitivity of lymphocyte counts and lymphocyte subtypes in the diagnosis and monitoring of frailty syndrome, and for this measure to be used as a biomarker of frailty status.
... Additionally, as adipose tissue expands and muscle and bone tissue decrease during aging for mostly females, there is an increase in pro-inflammatory markers which contributes to local and systematic inflammation. Reduced muscle fatigability might therefore explain the occurrence of fatigue, one of the key characteristics of physical frailty (Fried et al., 2001, Avlund et al., 2002a, Theou et al., 2008 and be more prevalent in females. Opposite results were found for disabilities in ADL, males ]) showed to have a higher risk compared to females ]), these results cannot be explained by sex differences but might be due to low study quality (lack of good statistical analysis and no reports on loss to follow up) of Avlund et al. (1995). ...
Article
Introduction Fatigue is a common complaint among older adults. Evidence grows that fatigue is linked to several negative health outcomes. A general overview of fatigue and its relationship with negative health outcomes still lacks in the existing literature. This brings complications for healthcare professionals and researchers to identify fatigue-related health risks. Therefore, this study gives an overview of the prospective predictive value of the main negative health outcomes for fatigue in community-dwelling older adults. Methods PubMed, Web of Knowledge and PsycINFO were systematically screened for prospective studies regarding the relationship between fatigue and negative health outcomes resulting in 4595 articles (last search 5th March 2020). Meta-analyses were conducted in RevMan using Odds ratios (ORs), Hazard ratios (HRs) and relative risk ratios (RR) that were extracted from the included studies. Subgroup-analyses were performed based on (1) gender (male/female), (2) length of follow-up and (3) fatigue level (low, medium and high). Results In total, thirty articles were included for this systematic review and meta-analysis encompassing 152 711 participants (age range 40-98 years), providing information on the relationship between fatigue and health outcomes. The results showed that fatigue is related to an increased risk for the occurrence of all studied health outcomes (range OR 1,299 – 3,094, HR/RR 1,038 – 1,471); for example, mortality OR 2.14 [1.74–2.63]; HR/RR 1.44 [1.28-1.62]), the development of disabilities in basic activities of daily living (OR 3.22 [2.05–5.38]), or the occurrence of physical decline (OR 1.42 [1.29–1.57]). Conclusion Overall fatigue increases the risk for developing negative health outcomes. The analyses presented in this study show that fatigue related physical decline occurs earlier than hospitalization, diseases and mortality, suggesting the importance of early interventions.
... This linear approach was shown to be a fair estimation of the real area under the curve (r = 0.98, p < 0.001) ( Bautmans et al., 2011), and is -given its simplicity and easiness to compute -excellent for clinical use. The FR test is now internationally accepted ( Theou et al., 2008) and several researchers as well as clinicians are using it (Elmahgoub et al., 2009;Theou et al., 2011;Calders et al., 2011;Alkurdi and Dweiri, 2010;Elmahgoub et al., 2011;D'Hooge et al., 2011;Drey et al., 2011). In several studies involving adolescents (with or without diabetes, obesities or mental retardation), researchers used the FR test to investigate if exercises training improved the muscle en- durance ( Elmahgoub et al., 2009;Calders et al., 2011;Elmahgoub et al., 2011;D'Hooge et al., 2011). ...
Article
Introduction Low Grip Work and high feelings of self-perceived fatigue could be an early characteristic of decline in reserve capacity, which comes to full expression as physical frailty in a later stage. When Grip Work and self-perceived fatigue can be identified as characteristics differentiating between robustness and pre-frailty it might allow to identify pre-frailty earlier. Therefore, this study aimed to investigate whether the combination of Grip Work and self-perceived fatigue is related to pre-frailty in well-functioning older adults aged 80 and over. Methods Four-hundred and five community-dwelling older adults aged 80 and over (214 robust and 191 pre-frail) were assessed for muscle endurance (Grip Work corrected for body weight (GW_bw)), self-perceived fatigue (MFI-20) and frailty state (Fried Frailty Index, FFI). A Capacity to Perceived Vitality ratio (CPV) was calculated by dividing GW_bw by the MFI-20 scores. ANCOVA analysis (corrected for age and gender) was used to compare robust and pre-frail older adults, and binary logistic regressions were applied to analyze the relationship between CPV and pre-frailty status. Results Pre-frail older adults who scored negative on the exhaustion item of the FFI still showed significantly lower GW (p < 0.001), CPV ratios (p < 0.001) and higher self-perceived fatigue (p < 0.05) compared to the robust ones. The likelihood for pre-frailty related significantly to higher age, being men and lower CPV ratios. In women, every unit increase in CPV ratio decreased the likelihood for pre-frailty by 78% (OR 0.22; 95% CI: 0.11–0.44), for men this effect was less strong (34%, OR 0.66; 95% CI: 0.47–0.93). Conclusions Pre-frail community-dwelling persons aged 80 years and over without clinical signs of exhaustion on the FFI still experience significantly higher fatigue levels (lower Grip Work, higher self-perceived fatigue and lower CPV levels) compared to robust ones. CPV ratio could therefore be a good tool to identify subclinical fatigue in the context of physical (pre-)frailty.
Conference Paper
Aging is associated with remarkable changes in body composition. Loss of skeletal muscle, a process called sarcopenia, is a prominent feature of these changes. In addition, gains in total body fat and visceral fat content continue into late life. The cause of sarcopenia is likely a result of a number of changes that also occur with aging. These include reduced levels of physical activity, changing endocrine function (reduced testosterone, growth hormone, and estrogen levels), insulin resistance, and increased dietary protein needs. Healthy free-living elderly men and women have been shown to accommodate to the Recommended Dietary Allowance (RDA) for protein of 0.8 g . kg(-1) . d(-1) with a continued decrease in urinary nitrogen excretion and reduced muscle mass. While many elderly people consume adequate amounts of protein, many older people have a reduced appetite and consume less than the protein RDA, likely resulting in an accelerated rate of sarcopenia. One important strategy that counters sarcopenia is strength conditioning. Strength conditioning will result in an increase in muscle size and this increase in size is largely the result of increased contractile proteins. The mechanisms by which the mechanical events stimulate an increase in RNA synthesis and subsequent protein synthesis are not well understood. Lifting weight requires that a muscle shorten as it produces force (concentric contraction). Lowering the weight, on the other hand, forces the muscle to lengthen as it produces force (eccentric contraction). These lengthening muscle contractions have been shown to produce ultrastructural damage (microscopic tears in contractile proteins muscle cells) that may stimulate increased muscle protein turnover. This muscle damage produces a cascade of metabolic events which is similar to an acute phase response and includes complement activation, mobilization of neutrophils, increased circulating an skeletal muscle interleukin-1, macrophage accumulation in muscle, and an increase in muscle protein synthesis and degradation. While endurance exercise increases the oxidation of essential amino acids and increases the requirement for dietary protein, resistance exercise results in a decrease in nitrogen excretion, lowering dietary protein needs. This increased efficiency of protein use may be important for wasting diseases such as HIV infection and cancer and particularly in elderly people suffering from sarcopenia. Research has indicated that increased dietary protein intake (up to 1.6 g protein . kg(-1) . d(-1)) may enhance the hypertrophic response to resistance exercise. It has also been demonstrated that in very old men and women the use of a protein-calorie supplement was associated with greater strength and muscle mass gains than did the use of placebo.
Article
This chapter discusses the current state of research on frailty, describing a number of competing and complementary models for its development. The concepts of allostasis and hormesis deal with the relationship between an organism and its environment. They may have particular relevance to frailty and could explain how early life events could have late-life consequences. Dysfunction of key organ systems might explain the phenomenon of frailty. This would include musculoskeletal abnormalities. Genotype and prenatal environment determine the birth phenotype. The specific nature of the prenatal environmental could lead to development plasticity, predictive adaptive responses, and developmental disruption. In a model based on a life course approach for the development of frailty, disability and healthcare utilization would be a consequence of frailty and modified by the relative assets and deficits of the individual. There is agreement that frailty is a syndrome encountered in older individuals that is marked by increased vulnerability to a number of adverse outcomes. Other hallmarks are the presence of multisystem impairment and the concept of a gradient. Although vulnerability is present up to a degree in all of us, frailty is marked by a greater than normal susceptibility.
Article
The original central fatigue hypothesis suggested that an exercise-induced increase in extracellular serotonin concentrations in several brain regions contributed to the development of fatigue during prolonged exercise. Serotonin has been linked to fatigue because of its well known effects on sleep, lethargy and drowsiness and loss of motivation. Several nutritional and pharmacological studies have attempted to manipulate central serotonergic activity during exercise, but this work has yet to provide robust evidence for a significant role of serotonin in the fatigue process. However, it is important to note that brain function is not determined by a single neurotransmitter system and the interaction between brain serotonin and dopamine during prolonged exercise has also been explored as having a regulative role in the development of fatigue. This revised central fatigue hypothesis suggests that an increase in central ratio of serotonin to dopamine is associated with feelings of tiredness and lethargy, accelerating the onset of fatigue, whereas a low ratio favours improved performance through the maintenance of motivation and arousal. Convincing evidence for a role of dopamine in the development of fatigue comes from work investigating the physiological responses to amphetamine use, but other strategies to manipulate central catecholamines have yet to influence exercise capacity during exercise in temperate conditions. Recent findings have, however, provided support for a significant role of dopamine and noradrenaline (norepinephrine) in performance during exercise in the heat. As serotonergic and catecholaminergic projections innervate areas of the hypothalamus, the thermoregulatory centre, a change in the activity of these neurons may be expected to contribute to the control of body temperature whilst at rest and during exercise. Fatigue during prolonged exercise clearly is influenced by a complex interaction between peripheral and central factors.
Article
Purpose: To test the hypothesis that leg blood flow and leg 0, extraction during peak exercise are reduced with age in healthy normally active women. Methods: Thirteen younger (20-27 yr) and 12 older (60-71 yr) nonendurance trained women performed graded upright leg cycling to maximum exertion (<(V)over dot>O-2peak), while leg blood flow (femoral vein thermodilution), cardiac output (acetylene rebreathing), mean arterial pressure (MAP, radial artery), and blood 02 contents were measured. Results: Peak leg <(V)over dot>O-2 was 32% lower in the older versus younger women (0.81 +/- 0.06 vs 1.18 +/- 0.10 L(.)min(-1)) and was correlated with peak systemic <(V)over dot>O-2 (1.33 +/- 0.1 vs 1.78 +/- 0.1 L(.)min(-1)) in both groups. Peak leg blood flow and estimated leg vascular conductance were 29% and 38% lower, respectively, in the older women (both P < 0.001). Peak leg blood flow and peak estimated cardiac output were correlated in the older (r(2) = 0.51, P = 0.02), but not younger (r(2) = 0.10, P = 0.35), group. Estimates of peak systemic and leg arterial-venous O-2 difference did not differ between groups (both P > 0.28). Conclusions: Reduced leg blood flow is a major contributor to the reduced peak systemic <(V)over dot>O-2 observed in older nonendurance trained women. Diminished leg blood flow during peak exercise in older women, in turn, is due to both central (reduced cardiac output) and peripheral (reduced leg vascular conductance) limitations.
Article
Purpose: To study the effect of creatine (Cr) supplementation combined with resistance training on muscular performance and body composition in older men. Methods: Thirty men were randomized to receive creatine supplementation (CRE, N = 16, age = 70.4 +/- 1.6 yr) or placebo (PLA, N = 14, age = 71.1 +/- 1.8 yr), using a double blind procedure. Cr supplementation consisted of 0.3-g Cr.kg(-1) body weight for the first 5 d (loading phase) and 0.07-g Cr.kg(-1) body weight thereafter. Both groups participated in resistance training (36 sessions, 3 times per week, 3 sets of 10 repetitions, 12 exercises). Muscular strength was assessed by 1-repetition maximum (1-RM) for leg press (LP), knee extension (KE), and bench press (BP). Muscular endurance was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-RM for BP and 80% baseline 1-RM for the KE and LP. Average power (AP) was assessed using a Biodex isokinetic knee extension/flexion exercise (3 sets of 10 repetitions at 60 degrees.s(-1) separated by 1-min rest). Lean tissue (LTM) and fat mass were assessed using dual energy x-ray absorptiometry. Results: Compared with PLA, the CRE group had significantly greater increases in LTM (CRE, +3.3 kg; PLA, +1.3 kg), LP 1-RM (CRE, +50.1 kg; PLA +31.3 kg), KE 1-RM (CRE, +14.9 kg; PLA, +10.7 kg), LP endurance (CRE, +47 reps; PLA, +32 reps), KE endurance (CRE, +21 reps; PLA +14 reps), and AP (CRE, +26.7 W; PLA, +18 W). Changes in fat mass, fat percentage, BP 1-RM, and BP endurance were similar between groups. Conclusion: Creatine supplementation, when combined with resistance training, increases lean tissue mass and improves leg strength, endurance, and average power in men of mean age 70 yr.