Muscle Growth Does Contribute to the Increases in Strength that Occur after Resistance Training

Optimizing Resistance Training for Sprint and Endurance Athletes: Balancing Positive and Negative Adaptations

Resistance training (RT) triggers diverse morphological and physiological adaptations that are broadly considered beneficial for performance enhancement as well as injury risk reduction. Some athletes and coaches therefore engage in, or prescribe, substantial amounts of RT under the assumption that continued increments in maximal strength capacity and/or muscle mass will lead to improved sports performance. In contrast, others employ minimal or no RT under the assumption that RT may impair endurance or sprint performances. However, the morphological and physiological adaptations by which RT might impair physical performance, the likelihood of these being evoked, and the training program specifications that might promote such impairments, remain largely undefined. Here, we discuss how selected adaptations to RT may enhance or impair speed and endurance performances while also addressing the RT program variables under which these adaptations are likely to occur. Specifically, we argue that while some myofibrillar (muscle) hypertrophy can be beneficial for increasing maximum strength, substantial hypertrophy can lead to macro- and microscopic adaptations such as increases in body (or limb) mass and internal moment arms that might, under some conditions, impair both sprint and endurance performances. Further, we discuss how changes in muscle architecture, fiber typology, microscopic muscle structure, and intra- and intermuscular coordination with RT may maximize speed at the expense of endurance, or maximize strength at the expense of speed. The beneficial effect of RT for sprint and endurance sports can be further improved by considering the adaptive trade-offs and practical implications discussed in this review.

Molecular aspects of the exercise response and training adaptation in skeletal muscle

Skeletal muscle plasticity enables an enormous potential to adapt to various internal and external stimuli and perturbations. Most notably, changes in contractile activity evoke a massive remodeling of biochemical, metabolic and force-generating properties. In recent years, a large number of signals, sensors, regulators and effectors have been implicated in these adaptive processes. Nevertheless, our understanding of the molecular underpinnings of training adaptation remains rudimentary. Specifically, the mechanisms that underlie signal integration, output coordination, functional redundancy and other complex traits of muscle adaptation are unknown. In fact, it is even unclear how stimulus-dependent specification is brought about in endurance or resistance exercise. In this review, we will provide an overview on the events that describe the acute perturbations in single endurance and resistance exercise bouts. Furthermore, we will provide insights into the molecular principles of long-term training adaptation. Finally, current gaps in knowledge will be identified, and strategies for a multi-omic and -cellular analyses of the molecular mechanisms of skeletal muscle plasticity that are engaged in individual, acute exercise bouts and chronic training adaptation discussed.

Effect of Different Load Intensity Transition Schemes on Muscular Strength and Physical Performance in Postmenopausal Women

PURPOSE

In postmenopausal women, optimizing muscular strength and physical performance through proper resistance training (RT) is crucial in achieving optimal functional reserve later in life. This study aimed to compare if a higher-load-to-lower-load (HL-to-LL) scheme is more effective than a lower-load-to-higher-load (LL-to-HL) scheme on muscular strength and physical performance in postmenopausal women after 12 and 24 wk of RT.

METHODS

Twenty-four postmenopausal women were randomized into two groups: LL-to-HL ( n = 12, 27-31 repetitions maximum (RM) in the first 12 wk, and 8-12RM in the last 12 wk) or HL-to-LL ( n = 12, 8-12RM during the first 12 wk, and 27-31RM in the last 12 wk). Muscular dynamic (1RM test) and isometric strength (MIVC) and functional tests (sit-to-stand power, 400-m walking, and 6-min walking) were analyzed at baseline, after 12 and 24 wk.

RESULTS

Different load intensity transition schemes resulted in enhancements ( P < 0.05) in dynamic (45° leg press: LL-to-HL = 21.98% vs HL-to-LL = 16.07%; leg extension: LL-to-HL = 23.25% vs HL-to-LL = 16.28%; leg curl: LL-to-HL = 23.89% vs HL-to-LL = 13.34%) and isometric strength (LL-to-HL = 14.63% vs HL-to-LL = 19.42%), sit-to-stand power (LL-to-HL = 7.32% vs HL-to-LL = 0%), and walking speed (400-m test: LL-to-HL = 3.30% vs HL-to-LL = 5.52%; 6-min test: LL-to-HL = 4.44% vs HL-to-LL = 5.55%) after 24 wk of RT, without differences between groups ( P > 0.05). However, only the HL increased the dynamic strength in 45° leg press and leg extension and sit-to-stand power. Moreover, walking speed changes were more strongly correlated with the changes in MIVC ( P < 0.05).

CONCLUSIONS

Our results indicate that both load intensity transition schemes produce similar improvements in muscular strength and physical performance in postmenopausal women after 24 wk of RT. However, the HL was more effective in increasing 45° leg press and leg extension strength, as well as power (mainly when performed after the LL), whereas having little effect on leg curl strength, isometric strength, and walking speed. Our findings suggest that although an HL makes a muscle isotonically stronger, it may have limited impact on isometric strength and walking speed in postmenopausal women.

Letter writing assignment for exercise physiology students

Letters to the editor are an important part of democratic societies. In academic journals, letters serve as a form of postpublication review and thus permit continued discussion and debate of scientific ideas. However, letters and their importance are rarely taught to university students. Therefore, the aim of the present paper is to propose a lecture and an assignment that introduce the exercise physiology student to letters. The lecture includes an overview of the history of letters, the definition and purposes of letters, letter themes, examples of letters published in exercise physiology journals, and a search method for discovering letters. The student is then assigned a project comprised of two parts. Part 1 requires the student to independently discover a letter exchange in a scientific journal, including the original research article, the letter commenting on the article, and the reply to the letter. The student then writes a report that summarizes the exchange. The report includes an analysis of the letter's themes and the validity of the arguments made. Part 2 of the assignment requires the student to independently discover an article published in the past year that they believe requires comment. The student then writes a letter, commenting on the article. Students who write convincing letters can be encouraged to submit their letter to the journal. The assignment should help prepare the next generation of journal editors, reviewers, and readers for the task of preserving and participating in a practice that serves to refine knowledge.NEW & NOTEWORTHY Letters to the editor are a form of postpublication review and thus help to refine knowledge through discussion and debate, yet exercise physiology students are rarely introduced to letters in their formal education. Here, the author proposes a lecture and an assignment that the university educator can use to help students understand the importance of letters. In the assignment, the student, among other tasks, critiques an existing letter exchange and writes a letter for potential publication.

Effects of Low- Versus High-Velocity-Loss Thresholds With Similar Training Volume on Maximal Strength and Hypertrophy in Highly Trained Individuals

AIMS

In the present intervention study, low-velocity-loss (LVL) versus high-velocity-loss (HVL) thresholds in the squat and bench press were compared for changes in muscle strength, power, and hypertrophy.

METHODS

Strength-trained volunteers (7♀ and 9♂; age: 27.2 [3.4] y; height: 174.6 [8.0] cm; body mass: 75.3 [10.1] kg) were randomized into an LVL or HVL threshold group (LVL n = 3♀ + 5♂, and HVL n = 4♀ + 4♂). Training took place 3 times per week over 6 weeks (loads: ∼75%-90% of 1-repetition maximum [1RM]). The thresholds of LVLs and HVLs were set at 20% and 40% of maximal velocity, respectively, for the squat, and at 30% and 60%, respectively, for the bench press. Before and after the intervention, 1RM, leg press power, and squat jump were tested. The load (∼45% of 1RM) corresponding to 1-m/s velocity was assessed in all sessions for both exercises. In addition, the thickness of the vastus lateralis and triceps brachii and body composition (dual-energy X-ray absorptiometry [DEXA]) were measured.

RESULTS

Squat and bench-press 1RM increased similarly in both groups by 7% to 11% (SD: 4%-6%, P < .05). No group differences were observed for changes in jump height, leg press power, or DEXA lean mass. However, HVL showed a small increase in muscle thickness of the vastus lateralis compared with LVL (6 ± 6% [95% CI] group difference, P < .05).

CONCLUSION

For strength-trained individuals, high-volume lower-velocity-loss thresholds were as effective as higher thresholds for improvements in 1RM strength; but local hypertrophy was seemingly elicited faster with higher velocity-loss thresholds.

Fish Oil for Healthy Aging: Potential Application to Master Athletes

Master athletes perform high volumes of exercise training yet display lower levels of physical functioning and exercise performance when compared with younger athletes. Several reports in the clinical literature show that long chain n-3 polyunsaturated fatty acid (LC n-3 PUFA) ingestion promotes skeletal muscle anabolism and strength in untrained older persons. There is also evidence that LC n-3 PUFA ingestion improves indices of muscle recovery following damaging exercise in younger persons. These findings suggest that LC n-3 PUFA intake could have an ergogenic effect in master athletes. However, the beneficial effect of LC n-3 PUFA intake on skeletal muscle in response to exercise training in both older and younger persons is inconsistent and, in some cases, generated from low-quality studies or those with a high risk of bias. Other factors such as the choice of placebo and health status of participants also confound interpretation of existing reports. As such, when considered on balance, the available evidence does not indicate that ingestion of LC n-3 PUFAs above current population recommendations (250–500 mg/day; 2 portions of oily fish per week) enhances exercise performance or recovery from exercise training in master athletes. Further work is now needed related to how the dose, duration, and co-ingestion of LC n-3 PUFAs with other nutrients such as amino acids impact the adaptive response to exercise training. This work should also consider how LC n-3 PUFA supplementation may differentially alter the lipid profile of cellular membranes of key regulatory sites such as the sarcolemma, mitochondria, and sarcoplasmic reticulum.