A combination of high levels of physical activity, low sex hormone concentrations and subsequent low bone mineral density is commonplace in athletic populations. Low bone mineral density can lead to an increased risk of stress reactions or fractures, which can significantly reduce sport participation time. The use of heavy strength training has been effective at increasing bone mineral density in older, frail osteoporotic populations, and there is evidence that it would also be effective in athletic populations with low bone density. In addition to potentially reducing the risk of stress reactions and fractures, heavy strength training may be beneficial for endurance performance, including when being used as a replacement for some of the endurance activities. Thus, individuals exhibiting symptoms associated with the Female Athlete Triad, the Exercise Hypogondal Male Condition or Relative Energy Deficiency in Sports should consider implementing heavy strength training as part of their exercise regimen.
Dietary polyphenols, such as curcumin, green tea catechins, and pomegranate extract, may have the ability to enhance the effectiveness of long-term training programs by managing training-induced inflammation. Enhanced recovery may translate to increased capacity to train and perform more effectively. The dietary polyphenol curcumin has been reported to block the action of COX-2 and NF-kB signaling and would allow for increased capacity to train leading to heightened adaptations and the potential for ergogenic outcomes. These actions are very similar to the targeted actions of non-steroidal anti-inflammatory drugs (NSAIDs), but without the side-effects of NSAIDs. This review will compare and contrast the known effects of curcumin and identify common design elements between existing studies. Through this critical review of the existing literature it is our goal to establish a set of best practices that could be applied to an athletic population that is interested in using oral curcumin supplementation as a recovery agent.
Temporal trends of youth muscular fitness (i.e., muscular strength, muscular power and local muscular endurance) indicate that contemporary children and adolescents are weaker and slower than previous generations. Consequently, this generation of millennials appear to be just as vulnerable as older adults to the inevitable consequences of muscle disuse and neuromuscular dysfunction. The modern-day construct of pediatric dynapenia describes an identifiable and treatable condition in youth characterized by low levels of muscular strength and power and consequent physical and psychosocial limitations not caused by neurologic or muscular disease. An interaction of modifiable physical and psychosocial factors can influence the development and progression of pediatric dynapenia. Without structured interventions that target strength deficits and build strength reserves in a supporting environment, the divergence in performance between weaker and stronger children may persist into adolescence because weaker youth may be unable to break through a so-called strength barrier. Regular participation in a well-designed youth resistance training program provides an opportunity for youth to enhance their health and fitness while acquiring the physical skills and behaviors that support an active lifestyle. New insights have highlighted the importance of initiating strength-building interventions early in life to optimize performance gains in other important components of physical fitness. Developmentally appropriate resistance training should be integrated into school- and community-based youth fitness programs and strength-building activities should take a more prominent position in public health physical activity recommendations for children and adolescents.
Athlete monitoring utilizing strength and conditioning as well as other sport performance data is increasing in practice and in research. While the usage of this data for purposes of creating more informed training programs and producing potential performance prediction models may be promising, there are some statistical considerations that should be addressed by those who hope to use this data. The purpose of this review is to discuss many of the statistical issues faced by practitioners as well as provide best practices recommendations. Single-subject designs (SSD) appear to be more appropriate for monitoring and statistically evaluating athletic performance than traditional group statistical methods. This paper discusses several SSD options available that produce measures of both statistical and practical significance. Additionally, this paper discusses issues related to heteroscedasticity, reliability, validity and provides recommendations for each. Finally, if data are incorporated into the decision-making process, it should be returned and utilized quickly. Data visualizations are often incorporated into this process and this review discusses issues and recommendations related to their clarity, simplicity, and distortion. Awareness of these issues and utilization of some best practice methods will likely result in an enhanced and more efficient decision-making process with more informed athlete development programs.
Mitochondria are essential energy-providing organelles that are required in the maintenance of healthy skeletal muscle. As such, the removal of damaged mitochondria, through mitophagy, is necessary to maintain mitochondrial quality. In aging muscle, mitochondrial content and function are often found to be reduced compared to young individuals. This occurs despite the fact that measures of mitophagy are elevated, suggesting that mitophagy is insufficiently high to remove all of the dysfunctional organelles in aging muscle. Recent evidence has shown that acute exercise promotes mitophagic signaling, leading to organelle degradation. This exercise-induced signaling is attenuated in aging muscle, suggesting that aging muscle loses its capacity for mitochondrial turnover in response to exercise. This contributes to the reduction in muscle health in elderly individuals. Chronic exercise training improves mitochondrial content and function, even in aging muscle, leading to reduced mitophagy signaling. Thus, exercise training should be prescribed for both young and elderly populations to promote the maintenance of a healthy mitochondrial pool, through the stimulation of both organelle biogenesis and mitophagy.
Myogenic contraction of vascular smooth muscle cells (VSMCs) in resistance arteries and arterioles plays a critical role in regulating peripheral resistance. Ion channels expressed in VSMCs control ion influx or efflux from the plasma membrane and endoplasmic reticulum to regulate membrane potential, which contributes to the regulation of vascular tone. With the depolarization of VSMC membranes, an elevation of intracellular calcium ion (Ca2+) concentration is mediated by voltage-gated Ca2+ channels and can trigger a vasoconstrictive response. In addition, potassium ion (K+) efflux through K+ channels can hyperpolarize VSMCs, resulting in vasodilation. However, in the pathophysiological progression of diseases such as hypertension, VSMCs undergo a wide range of pathological changes, among them is “electrical remodeling”, which refers to changes in ion channels. Under physiological or pathological conditions, exercise has a profound impact on the human body, and ion channels are an essential target of the beneficial adaptive responses. This review provides insight on the physiological function of ion channels in VSMCs, including CaV1.2 channels, voltage-gated K+ channels, large-conductance Ca2+-activated K+ channels, and inward-rectifier K+ channels, and the changes of these ion channels during hypertension. Focus is given to the effects of exercise on these ion channels and its implications in disease treatment.
The purpose of this study was to examine the effects of caffeine on peak torque (PT), rate of torque development (RTD), and muscle activation in college-age men.
Fifteen men (23.3 ± 2.2 years, 177.6 ± 8.7 cm, 90.3 ± 19.1 kg) volunteered to participate in this study. During each of two test sessions, maximal leg extension PT and RTD were determined and electromyographic (EMG) and mechanomyographic (MMG) signals were collected to examine electrical and mechanical aspects of muscle activation, respectively. Participants also performed the Wingate Anaerobic Test (WAnT) for the determination of peak power (PP), mean power (MP), and fatigue percentage (FP). For the first test session, participants were randomly assigned to ingest either a caffeinated drink (6 mg/kg) or a placebo 1 h prior to testing. The second test session was identical to the first, but the drink not previously administered was ingested prior to testing.
The results indicated there were no significant effects of caffeine on PT, PP, MP, FP, or EMG and MMG measures. However, RTD was positively affected by caffeine (856.4 ± 246.4 Nm/s) compared to the placebo condition (710.9 ± 267.9 Nm/s).
These results suggest that caffeine can be an effective aid for sport activities requiring maximal rates of force or torque development during very short time periods.
The concept of post-activation potentiation (PAP) is still novel from a training perspective and lacks breadth relative to weightlifting exercises.
The purpose of this study was to investigate the acute effects of a conditioning activity (clean high pulls) on the performance of a main activity (clean) after the conditioning activity.
Eleven volunteers who engaged in weightlifting (Male = 5, Female = 6) participated in two different testing sessions (experimental vs. control). Baseline measurements were taken following the warm-up. The testing condition was performed and additional measurements were taken at 30 s, 2 min, 4 min, 6 min, 8 min, 10 min, and 12 min into recovery. A linear position transducer was used to collect peak power, peak velocity, and displacement of the barbell during the clean. Multiple 2 × 8 repeated measures ANOVAs were used to analyze the data along with a paired samples t test between baseline and “best” values.
There was no interaction or main effect for condition (P > 0.05). However, there was a significant main effect for time (P < 0.05) for all variables. The “best” values were significantly (P < 0.05) greater than baseline values (peak power: experimental = 1354.76 ± 521.24 W vs. baseline 1216.03 ± 492.30 W; peak velocity: experimental = 2.66 ± 0.44 m/s vs. baseline 2.50 ± 0.44 m/s; displacement: experimental = 111.07 ± 12.09 cm vs. baseline 107.01 ± 11.32 cm).
The findings of this study are in partial agreement with previous literature where the warm-up was probably enough to elicit PAP. Therefore, recommendations for future studies could include utilizing a more elite population and to ensure all potential participants can squat at least 2 × their body weight.
The purpose of the study was to investigate the effects of using compound sets during a 12-week lower body resistance training program on muscle strength, endurance, hypertrophy, architecture, and soreness. Thirty-one recreationally active females were randomly assigned to one of three groups: traditional sets, compound sets, or control. The training groups performed Smith Machine squat and leg press at matched intensities, volumes, and cumulative rest per session. During compound sets, the squat was performed immediately prior to the leg press, while 1 min rest separated the exercises during traditional sets. A non-exercise control group did not perform resistance training. One-repetition maximum strength, muscle endurance, muscle thickness, cross-sectional area, pennation angle, training session time, and soreness were compared from pre- to post-training (α level < 0.05). Squat and leg press muscle strength and endurance were significantly increased following compound and traditional sets (P < 0.001). Compound and traditional sets were greater than the control group’s post-test 1-RM strength and muscle endurance on squat and leg press (P < 0.05). Cross-sectional area and muscle thickness increased after compound and traditional set training from pre- to post-training (P < 0.05). Neither training group had changes to pennation angle. There were no differences between training time per session, as well as subjective soreness at 12 (P > 0.80), 24 (P > 0.50), or 48 (P > 0.30) h post-workout. In conclusion, compound set training, with equated rest, is a method of resistance training that elicits gains similar to traditional sets in young females.
Gait speed is now recognized as an important clinical tool in the older adult population. However, fast gait speed appears to better reflect lower-extremity muscle performance and declines more rapidly in advanced age than comfortable gait speed. We examined the ability of leg lean mass and absolute and rapid strength characteristics to predict fast gait speed in younger versus older adults. Twenty-four younger (12 men, 12 women; age = 22 ± 3 years) and 22 older (11 men, 11 women; age = 72 ± 6 years) adults participated in the study. Fast gait speed was assessed at 10- and 400-m distances. Leg lean mass was quantified with dual X-ray absorptiometry. Isometric squat peak torque and the rate of torque development at 200 ms (RTD200) were tested with a 120° knee joint angle. Statistical analyses included independent samples t tests, partial correlations, and stepwise regression. Large differences between age groups were observed for peak torque, RTD200, and gait speed (P ≤ 0.006, d ≥ 0.79), whereas the difference in leg lean mass was small (P = 0.246, d = 0.35). In older adults only, the partial correlation for 400-m speed versus RTD200 was significant (r = 0.463, P = 0.040). Stepwise regression revealed that peak torque was a significant predictor of 10-m (R 2 = 0.257, P = 0.016) and 400-m (R 2 = 0.239, P = 0.021) gait speed in older adults. As adults age, lower-extremity, multi-joint muscle strength becomes increasingly important in regulating fast gait speed, whereas lean mass is not predictive.
Strength and power are important traits for law enforcement officers, but the relationship between these measures has yet to be determined in a law enforcement population. Furthermore, the nature for these relationships between officers of varying strength is not known. The purpose of this study was to investigate the relationship between strength and measures of power and to determine whether stronger officers portrayed greater power. Retrospective data for 543 male (age = 39.07 ± 8.04 years; height = 180.02 ± 15.14 cm; body mass = 92.73 ± 16.37 kg) officers from one agency were provided. Measures included isometric leg/back dynamometer (LBD) strength, a counter movement jump (CMJ) and further determined measures of lower body power [estimated anaerobic power in watts (PAPw)] and power to body mass ration (P:BM). Following an analysis by cohort, subgroup quartiles were created based off LBD strength [absolute (LBDa) and relative (LBDr)]. The strongest quartile (Q1) performed significantly better in CMJ and PAPw than the other groups, but not in P:BM. Significant (P ≤ 0.001) low-to-moderate positive correlations were found between LBDa and CMJ height (r = 0.388), PAPw (r = 0.606) and P:BM (r = 0.272) and between LBDr and CMJ (r = 0.556), P:BM (r = 0.642) and PAPw (r = 0.149). Only LBDr was significantly related to all power measures across all sub groups. The development of relative lower body strength may best prepare officers for power assessments (such as vertical jump assessments) as well as for occupational tasks that require power.