Multimodal and conventional resistance training interventions improve muscle function in older adults: Findings from the Training IMCT study.

Age-associated remodeling processes affect the intramuscular connective tissue (IMCT) network, which may significantly impair muscle function. Thus, we aimed to test whether including exercises shown to efficiently target the IMCT to a conventional resistance exercise intervention (CONV) would result in greater functional gains as compared to CONV alone. Fifty-three men and women (66.2 ± 3.3 years) were assigned to either CONV (n = 15), multimodal training (MULTI; n = 17) or a control (CTRL; n = 21) group. All subjects were tested at baseline, and those assigned to CONV or MULTI underwent a 16-week training intervention. The CONV group followed a progressive resistance training program, in which the number of weekly training sessions gradually increased from 1 to 3. In the MULTI group, one of these sessions was replaced with plyometric training, followed by self-myofascial release. Testing included maximal strength and power, imaging-based muscle volume, architecture, and functional performance. The intervention effects were analyzed using two- or three-way repeated measures ANOVA models (α = 0.05). Briefly, the maximal knee extension isometric contraction, one-repetition maximum, and isokinetic peak torque increased in all groups (p < 0.05), albeit to a lesser extent in CTRL. On the other hand, quadriceps femoris muscle volume (p = 0.019) and vastus lateralis pennation angle (p < 0.001) increased only in the MULTI group. Handgrip strength did not change in response to the intervention (p = 0.312), whereas Sit-to-Stand performance improved in all groups after the first 8-wks, but only in MULTI and CONV after 16-wks (all p < 0.001). In conclusion, we found that a resistance training intervention in which one weekly training session is replaced by plyometric training is feasible and as effective as a program consisting solely of conventional strength training sessions for inducing gains in muscle strength and function in older adults. Muscle size and architecture improved only in the MULTI group. German Clinical Trials: DRKS00015750.

Remodeling the Skeletal Muscle Extracellular Matrix in Older Age-Effects of Acute Exercise Stimuli on Gene Expression.

With advancing age, the skeletal muscle extracellular matrix (ECM) undergoes fibrotic changes that may lead to increased muscle stiffness, injury susceptibility and strength loss. This study tested the potential of different exercises to counter these changes by stimulating the activity of genes associated with ECM remodeling. Twenty-six healthy men (66.9 ± 3.9 years) were stratified to two of four groups, performing unilateral (i) conventional resistance exercise, (ii) conventional resistance exercise followed by self-myofascial release (CEBR), (iii) eccentric-only exercise (ECC) or (iv) plyometric jumps (PLY). The non-trained leg served as control. Six hours post-exercise, vastus lateralis muscle biopsy samples were analyzed for the expression of genes associated with ECM collagen synthesis (COL1A1), matrix metallopeptidases (collagen degradation; MMPs) and peptidase inhibitors (TIMP1). Significant between-group differences were found for MMP3, MMP15 and TIMP1, with the greatest responses in MMP3 and TIMP1 seen in CEBR and in MMP15 in ECC. MMP9 (3.24-3.81-fold change) and COL1A1 (1.47-2.40-fold change) were increased in CEBR and PLY, although between-group differences were non-significant. The expression of ECM-related genes is exercise-specific, with CEBR and PLY triggering either earlier or stronger remodeling than other stimuli. Training studies will test whether execution of such exercises may help counter age-associated muscle fibrosis.

An evaluation of prevention initiatives by 53 national anti-doping organizations: Achievements and limitations.

BACKGROUND: One main purpose of the World Anti-Doping Agency was to harmonize anti-doping efforts, including the provision of anti-doping education. A multifaceted approach to doping prevention can play a key role in preventing intentional and unintentional doping. This article aimed to systematically record and evaluate doping prevention approaches in the form of information and education activities of national anti-doping organizations (NADOs) and assess the extent to which a multifaceted doping prevention approach has been realized. METHODS: Data on anti-doping information and education activities of 53 NADOs were collected via a survey and an online search of the NADOs' websites. Prevention activities were classified into knowledge focused, affective focused, social skills, life skills, and ethic- and value- based. The implementation of the prevention activities was assessed by 4 independent raters using a modified visual analogue scale. RESULTS: In total, 59% of the NADOs (n = 38) returned the survey and 70% (n = 45) had information available online. The data were combined for the visual analogue scale assessment. Overall, 58% of the NADOs (n = 37) reported offering activities including elements of all 5 approaches. Results of the raters' assessments indicated that the knowledge-focused approach was best implemented; the implementation of the other 4 approaches was largely unsatisfactory. The most common barriers to implementing doping prevention programs reported by the NADOs were lack of resources (n = 26) and difficulties in collaborating with sports organizations (n = 8). CONCLUSION: Results show a discrepancy between NADOs' self-report data and the implementation assessment. Even though the NADOs indicated otherwise, most of their education-based approaches did not address aspects of the visual analogue scale (e.g., resisting peer pressure) and only a few programs were ongoing. Possible explanations might be found in the reported barriers (e.g., financial). Concrete guidelines defining multifaceted, values-based education, and best practice examples should be developed to indicate how to include all 5 approaches in prevention.

Skeletal Muscle Extracellular Matrix - What Do We Know About Its Composition, Regulation, and Physiological Roles? A Narrative Review.

Skeletal muscle represents the largest body-composition component in humans. In addition to its primary function in the maintenance of upright posture and the production of movement, it also plays important roles in many other physiological processes, including thermogenesis, metabolism and the secretion of peptides for communication with other tissues. Research attempting to unveil these processes has traditionally focused on muscle fibers, i.e., the contractile muscle cells. However, it is a frequently overlooked fact that muscle fibers reside in a three-dimensional scaffolding that consists of various collagens, glycoproteins, proteoglycans, and elastin, and is commonly referred to as extracellular matrix (ECM). While initially believed to be relatively inert, current research reveals the involvement of ECM cells in numerous important physiological processes. In interaction with other cells, such as fibroblasts or cells of the immune system, the ECM regulates muscle development, growth and repair and is essential for effective muscle contraction and force transmission. Since muscle ECM is highly malleable, its texture and, consequently, physiological roles may be affected by physical training and disuse, aging or various diseases, such as diabetes. With the aim to stimulate increased efforts to study this still poorly understood tissue, this narrative review summarizes the current body of knowledge on (i) the composition and structure of the ECM, (ii) molecular pathways involved in ECM remodeling, (iii) the physiological roles of muscle ECM, (iv) dysregulations of ECM with aging and disease as well as (v) the adaptations of muscle ECM to training and disuse.

Field-Derived Power-Duration Variables to Predict Cycling Time-Trial Performance.

PURPOSE: To evaluate the predictive validity of critical power (CP) and the work above CP (W') on cycling performance (mean power during a 20-min time trial; TT20). METHODS: On 3 separate days, 10 male cyclists completed a TT20 and 3 CP and W' prediction trials of 1, 4, and 10 min and 2, 7, and 12 min in field conditions. CP and W' were modeled across combinations of these prediction trials with the hyperbolic, linear work/time, and linear power inverse-time (INV) models. The agreement and the uncertainty between the predicted and actual TT20 were assessed with 95% limits of agreement and a probabilistic approach, respectively. RESULTS: Differences between the predicted and actual TT20 were "trivial" for most of the models if the 1-min trial was not included. Including the 1-min trial in the INV and linear work/time models "possibly" to "very likely" overestimated TT20. The INV model provided the smallest total error (ie, best individual fit; 6%) for all cyclists (305 [33] W; 19.6 [3.6] kJ). TT20 predicted from the best individual fit-derived CP, and W' was strongly correlated with actual TT20 (317 [33] W; r = .975; P < .001). The bias and 95% limits of agreement were 4 (7) W (-11 to 19 W). CONCLUSIONS: Field-derived CP and W' accurately predicted cycling performance in the field. The INV model was most accurate to predict TT20 (1.3% [2.4%]). Adding a 1-min-prediction trial resulted in large total errors, so it should not be included in the models.