Less Is More: The Physiological Basis for Tapering in Endurance, Strength, and Power Athletes

Sex Differences in Training Behaviors of 10 km to Ultra-Endurance Runners (Part A)-Results from the NURMI Study (Step 2)

Training for running events is fundamental for successful participation in various running events such as 10 km, half-marathon, marathon, or ultra-marathon distances. Training behaviors are likely based on runner motivations and social constraints, particularly for females. Participants completed a questionnaire following a cross-sectional approach, including questions on sociodemographics, general training behaviors, and periodization training strategies. The final sample included 245 participants (141 females, 104 males), mostly from Germany (72%), Austria (18%), and Switzerland (5%), with a median age of 39 years (IQR 17) and a BMI of 21.7 kg/m² (IQR 3.5). Males more often trained alone and independently, whereas females were most likely to follow an external resource (p = 0.037). Non-parametric ANOVA revealed significant training differences between sexes in daily training mileages and durations at each phase and stage (p < 0.05) as well as in weekly training mileages and durations for general basic training and race-specific training (p < 0.05). Critical sex differences in training behaviors may arise from physiological differences and social expectations, which may be related to the distances they prefer to race at as well as their motivations for running and racing. This study provides a wide overview of training behaviors for endurance runners or professionals guiding healthy running performance.

Correlation of Pre-Race Anxiety Using the Generalized Anxiety Disorder 2-Item Scale

An estimated 40 million adults in the United States have been diagnosed with an anxiety disorder, making it the most common psychiatric disorder in the country. Although the data are conflicting and limited, engaging in or increasing exercise has been proposed for the management of anxiety and other mental health disorders. The purpose of this study was to determine if there is a correlation between pre-race anxiety and running experience, sex, body mass index, age, and mental health history using the validated Generalized Anxiety Disorder 2-Item screening tool for anxiety. This study was a prospective trial of 403 adult runners who were scheduled to participate in a 5 K, 10 K, half marathon, or full marathon race. Each participant completed a survey consisting of epidemiologic variables and the Generalized Anxiety Disorder 2-Item screening tool. Results revealed that the runners with more experience and increased mileage demonstrated a decrease in reported worrying on a daily to near-daily basis; whether this finding correlates with a decreased risk of developing an anxiety disorder has yet to be determined. Based on our findings, exercise as a prescription for the treatment and possibly prevention of anxiety should be considered.

The effects of high-intensity functional training on cardiometabolic risk factors and exercise enjoyment in men and women with metabolic syndrome: study protocol for a randomized, 12-week, dose-response trial

Background

Individuals with metabolic syndrome (MetS) are at a greater risk for developing atherosclerotic cardiovascular disease (ASCVD) than those without MetS, due to underlying endothelial dysfunction, dyslipidemia, and insulin resistance. Exercise is an effective primary and secondary prevention strategy for MetS; however, less than 25% of adults meet the minimum stated public recommendations. Barriers often identified are lack of enjoyment and lack of time. High-intensity functional training (HIFT), a time-efficient modality of exercise, has shown some potential to elicit positive affectivity and elicit increased fitness and improved glucose metabolism. However, the effects of HIFT on dyslipidemia and endothelial dysfunction have not been explored nor have the effects been explored in a population with MetS. Additionally, no studies have investigated the minimal dose of HIFT per week to see clinically meaningful changes in cardiometabolic health. The purpose of this study is to (1) determine the dose-response effect of HIFT on blood lipids, insulin resistance, and endothelial function and (2) determine the dose-response effect of HIFT on body composition, fitness, and perceived enjoyment and intention to continue the exercise.

Methods/design

In this randomized, dose-response trial, participants will undergo a 12-week HIFT intervention of either 1 day/week, 2 days/week, or 3 days/week of supervised, progressive exercise. Outcomes assessed at baseline and post-intervention will be multiple cardiometabolic markers, and fitness. Additionally, the participant’s affective response will be measured after the intervention.

Discussion

The findings of this research will provide evidence on the minimal dose of HIFT per week to see clinically meaningful improvements in the risk factors of MetS, as well as whether this modality is likely to mitigate the barriers to exercise. If an effective dose of HIFT per week is determined and if this modality is perceived positively, it may provide exercise specialists and health care providers a tool to prevent and treat MetS.

Trial registration

ClinicalTrials.gov NCT05001126. August 11, 2021.

Muscle Fiber Type Transitions with Exercise Training: Shifting Perspectives

Human muscle fibers are generally classified by myosin heavy chain (MHC) isoforms characterized by slow to fast contractile speeds. Type I, or slow-twitch fibers, are seen in high abundance in elite endurance athletes, such as long-distance runners and cyclists. Alternatively, fast-twitch IIa and IIx fibers are abundant in elite power athletes, such as weightlifters and sprinters. While cross-sectional comparisons have shown marked differences between athletes, longitudinal data have not clearly converged on patterns in fiber type shifts over time, particularly between slow and fast fibers. However, not all fiber type identification techniques are created equal and, thus, may limit interpretation. Hybrid fibers, which express more than one MHC type (I/IIa, IIa/IIx, I/IIa/IIx), may make up a significant proportion of fibers. The measurement of the distribution of fibers would necessitate the ability to identify hybrid fibers, which is best done through single fiber analysis. Current evidence using the most appropriate techniques suggests a clear ability of fibers to shift between hybrid and pure fibers as well as between slow and fast fiber types. The context and extent to which this occurs, along with the limitations of current evidence, are discussed herein.

Inter- and Intra-Day Comparisons of Smartphone-Derived Heart Rate Variability across Resistance Training Overload and Taper Microcycles

The purposes of this study were: (1) to determine if smartphone-derived heart rate variability (HRV) could detect changes in training load during an overload microcycle and taper, and (2) to determine the reliability of HRV measured in the morning and measured immediately prior to the testing session. Twelve powerlifters (male = 10, female = 2) completed a 3-week resistance training program consisting of an introduction microcycle, overload microcycle, and taper. Using a validated smartphone application, daily measures of resting, ultra-short natural logarithm of root mean square of successive differences were recorded in the morning (LnRMSSD_M) and immediately before the test session (LnRMSSD_T) following baseline, post-overload, and post-taper testing. LnRMSSD_M decreased from baseline (82.9 ± 13.0) to post-overload (75.0 ± 9.9, p = 0.019), while post-taper LnRMSSD_M (81.9 ± 7.1) was not different from post-overload (p = 0.056) or baseline (p = 0.998). No differences in LnRMSSD_T (p < 0.05) were observed between baseline (78.3 ± 9.0), post-overload (74.4 ± 10.2), and post-taper (78.3 ± 8.0). LnRMSSD_M and LnRMSSD_T were strongly correlated at baseline (ICC = 0.71, p < 0.001) and post-overload (ICC = 0.65, p = 0.010), whereas there was no relationship at post-taper (ICC = 0.44, p = 0.054). Bland–Altman analyses suggest extremely wide limits of agreement (Bias ± 1.96 SD) between LnRMSSD_M and LnRMSSD_T at baseline (4.7 ± 15.2), post-overload (0.5 ± 16.9), and post-taper (3.7 ± 15.3). Smartphone-derived HRV, recorded upon waking, was sensitive to resistance training loads across an overload and taper microcycles in competitive strength athletes, whereas the HRV was taken immediately prior to the testing session was not.

Choreography-Specific Cross-Training and Conditioning Programs

Because of increased choreographic demands, early specialization, multi-genre dancers, and high incidence of career-ending injuries, there is a need for enhanced training methodologies to address the unique needs of today's professional dancer. It is imperative for company directors, instructors, choreographers, and dance medicine practitioners to consider implementing the most specific conditioning and training programs to prepare their dancers to meet or exceed expectations without resultant injury. Quantifying effectiveness of choreography-specific training programs is an area for further research. The implementation of scientific principles can and should be used to enhance dancers' health, performance, athleticism, and artistry.

High-Intensity Interval Training Shock Microcycle for Enhancing Sport Performance: A Brief Review

Dolci, F, Kilding, AE, Chivers, P, Piggott, B, and Hart, NH. High-intensity interval training shock microcycle for enhancing sport performance: A brief review. J Strength Cond Res 34(4): 1188-1196, 2020-High-intensity interval training (HIIT) is a powerful strategy to develop athletes' fitness and enhance endurance performance. Traditional HIIT interventions involve multiple microcycles (7-10 days long) of 2-3 HIIT sessions each, which have been commonly supported to improve athletic performance after a minimum period of 6 weeks training. Regardless of the efficacy of such an approach, in recent years, a higher frequency of HIIT sessions within a unique microcycle, commonly referred to as an HIIT shock microcycle, has been proposed as an alternative HIIT periodization strategy to induce greater and more efficient endurance adaptation in athletes. This review article provides an insight into this new HIIT periodization strategy by discussing (1) HIIT shock microcycle format and design; (2) the sustainability of this training strategy; (3) effects on performance and physiological parameters of endurance; and (4) potential mechanisms for improvements. Evidence advocates the sustainability and effectiveness of HIIT shock microcycle in different athletes to improve intermittent and continuous running/cycling performance and suggests mitochondria biogenesis as the main acute physiological adaptation following this intervention.

Pacing and Performance in Swimming: Differences Between Individual and Relay Events

PURPOSE

Although pacing is considered crucial for success in individual swimming events, there is a lack of research examining pacing in relays. The authors investigated the impact of start lap and pacing strategy on swimming performance and whether these strategies differ between relays and the corresponding individual event.

METHODS

Race data for 716 relay (4 × 200-m freestyle) finals from 14 international competitions between 2010 and 2018 were analyzed retrospectively. Each swimmer's individual 200-m freestyle season's best time for the same year was used for comparison. Races were classified as a fast, average, or slow start lap strategy (lap 1) and as an even, negative, or positive pacing strategy (laps 2-4) to give an overall race strategy, for example, average start lap even pacing.

RESULTS

A fast start lap strategy was associated with slower 200-m times (range 0.5-0.9 s, P ≤ .04) irrespective of gender, and positive pacing led to slower 200-m (0.4-0.5 s, P ≤ .03) times in females. A fast start lap strategy led to positive pacing in 71% of swimmers. Half of the swimmers changed pacing strategy, with 13% and 7% more female and male swimmers, respectively, displaying positive pacing in relays compared with individual events. In relays, a fast start lap and positive pacing was utilized more frequently by swimmers positioned on second to fourth relay legs (+13%) compared with lead-off leg swimmers (+3%).

CONCLUSION

To maximize performance, swimmers should be more conservative in the first lap and avoid unnecessary alterations in race strategy in relay events.

Periodized Resistance Training for Enhancing Skeletal Muscle Hypertrophy and Strength: A Mini-Review

Prescribing the proper resistance training (RT) program is critical to optimize skeletal muscle hypertrophy and strength. Periodization is a strategy that entails planned manipulations of training variables to maximize fitness adaptations while minimizing the risk of overtraining. Multiple meta-analyses have shown periodized RT to be superior to non-periodized RT for enhancing muscular strength. These findings are consistent irrespective of training status or training volume. Both the linear model and the undulating model are effective for enhancing strength, although a greater benefit might be achieved through the undulating model. Despite the suggested superiority of periodized RT for strength development, some authors suggest that this might be a consequence of the study designs employed rather than the nature of periodized training. In addition, several limitations exist in the periodization literature, making it difficult to accurately assess the efficacy of periodized RT. With regard to enhancing skeletal muscle hypertrophy, both the undulating model and the linear model appear equally effective; however, this conclusion can only be generalized to untrained populations. When comparing periodized RT to non-periodized RT programs, the research is unclear on whether periodized RT is necessary to maximize skeletal muscle hypertrophy.

Aging-related effects of bed rest followed by eccentric exercise rehabilitation on skeletal muscle macrophages and insulin sensitivity

The pro- and anti-inflammatory macrophages are associated with insulin sensitivity and skeletal muscle regeneration. Infiltrating macrophages in skeletal muscle during a period of physical inactivity and subsequent reloading/rehabilitation in older adults is unknown, but may provide insight into mechanisms related to the development of metabolic disease and changes in muscle cell size. The purpose of this study was to determine if skeletal muscle macrophage infiltration is modulated differently between young and older adults after bed rest and exercise rehabilitation and if these responses are related to muscle and insulin sensitivity changes. 14 young and 9 older adults underwent 5-days of bed rest followed by 8-weeks of lower limb eccentric exercise rehabilitation (REHAB). Dual-energy X-ray absorptiometry, magnetic resonance imaging and myofiber analysis were used to identify muscle morphology and CLIX-IR and CLIX-β were used to assess insulin sensitivity. Skeletal muscle macrophages, CD68 (pan), CD11b (M1), CD163 (M2), CD206 (M2), were characterized using immunohistochemistry and gene expression. Insulin sensitivity, independent of age, decreased ~38% following bed rest and was restored following REHAB. We found robust age-related differences in muscle atrophy during bed rest, yet older and younger adults equally hypertrophied during REHAB. Interestingly, there were age-related differences in macrophage content (CD68⁺CD11b⁺ and CD68⁺CD11b^- cells) but both young and old similarly increased macrophages with REHAB. Satellite cell changes during rehab corresponded to macrophage content changes. Muscle tissue resident macrophages and gene expression, were not associated with changes in insulin sensitivity following bed rest and REHAB. These data suggest that muscle macrophages are modulated as a result of exercise rehabilitation following bed rest and may more associated with muscle regrowth/hypertrophy rather than insulin sensitivity in young or older adults. This trial was registered at clinicaltrials.gov as NCT01669590.