Sex differences in skeletal muscle fiber types: A meta-analysis.

Biopsies have been acquired from living men and women to determine proportions of Type I (slow-twitch) and II (fast-twitch) skeletal muscle fibers since the 1970s. Sex differences have been assumed but the literature has not been submitted to meta-analysis. Here, the aim was to generate effect sizes of sex differences in muscle fiber cross-sectional areas, distribution percentages, and area percentages. Data from 2875 men and 2452 women, who participated in 110 studies, were analyzed. Myofibrillar adenosine triphosphatase histochemistry was used in 71.8% of studies to classify fibers as Type I, II, IIA, and/or IIX; immunohistochemistry, immunofluorescence, or sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used in 35.4% of studies to similarly classify myosin heavy chain (MHC) isoform content. Most studies involved biopsies from vastus lateralis (79.1%) in healthy individuals (92.7%) between 18 and 59 years old (80.9%). Men exhibited greater cross-sectional areas for all fiber types (g = 0.40-1.68); greater distribution percentages for Type II, MHC II, IIA, IIX fibers (g = 0.26-0.34); greater area percentages for Type II, IIA, MHC IIA, IIX fibers (g = 0.39-0.93); greater Type II/I and Type IIA/I fiber area ratios (g = 0.63, 0.94). Women exhibited greater Type I and MHC I distribution percentages (g = -0.13, -0.44); greater Type I and MHC I area percentages (g = -0.53, -0.69); greater Type I/II fiber area ratios (g = -1.24). These data, which represent the largest repository of comparative muscle fiber type data from living men and women, can inform discussions about biological sex and its impact on pathologies and sports performance (e.g., explaining sex differences in muscle strength and muscle endurance).

Muscle Strength Preservation During Repeated Sets of Fatiguing Resistance Exercise: A Secondary Analysis.

ABSTRACT: Nuzzo, JL. Muscle strength preservation during repeated sets of fatiguing resistance exercise: A secondary analysis. J Strength Cond Res 38(6): 1149-1156, 2024-During sustained or repeated maximal voluntary efforts, muscle fatigue (acute strength loss) is not linear. After a large initial decrease, muscle strength plateaus at approximately 40% of baseline. This plateau, which likely reflects muscle strength preservation, has been observed in sustained maximal isometric and repeated maximal isokinetic contractions. Whether this pattern of fatigue occurs with traditional resistance exercise repetitions with free weights and weight stack machines has not been overviewed. Here, the aim was to determine whether the number of repetitions completed across 4 or more consecutive repetitions-to-failure tests exhibits the same nonlinear pattern of muscle fatigue. A secondary analysis was applied to data extracted as part of a recent meta-analysis on repetitions-to-failure tests. Studies were eligible if they reported mean number of repetitions completed in 4-6 consecutive repetitions-to-failure tests at a given relative load. Twenty-nine studies were included. Overall, the results show that the number of repetitions completed in consecutive repetitions-to-failure tests at a given load generally decreases curvilinearly. The numbers of repetitions completed in sets 2, 3, 4, 5, and 6 were equal to approximately 70, 55, 50, 45, and 45% of the number of repetitions completed in set 1, respectively. Longer interset rest intervals typically attenuated repetition loss, but the curvilinear pattern remained. From the results, a chart was created to predict the number of repetitions across 6 sets of resistance exercise taken to failure based on the number of repetitions completed in set 1. The chart is a general guide and educational tool. It should be used cautiously. More data from a variety of exercises, relative loads, and interset rest intervals are needed for more precise estimates of number of repetitions completed during repeated sets of fatiguing resistance exercise.

Men and women differ in their interest and willingness to participate in exercise and sports science research.

Unequal proportions of male and female participants in exercise research might be attributed, in part, to differences in interest and willingness to participate. We tested if men and women are equally interested and willing to undergo exercise research procedures and if they consider different factors when deciding to participate. Two samples completed an online survey. Sample 1 (129 men, 227 women) responded to advertisements on social media and survey-sharing websites. Sample 2 (155 men, 504 women) was comprised of undergraduate psychology students. In both samples, men were significantly more interested to learn their muscle mass amount, running speed, jump height, and ball throwing ability, and more willing to receive electrical shocks, cycle or run until exhaustion, complete strength training that causes muscle soreness, and take muscle-building supplements (all p ≤ 0.013, d = 0.23-0.48). Women were significantly more interested to learn their flexibility, and more willing to complete surveys, participate in stretching and group aerobics interventions, and participate in home exercise with online instruction (all p ≤ 0.021, d = 0.12-0.71). Women rated the following significantly more important when deciding to participate: study's implications for society; personal health status; confidence in own abilities; potential anxiety during testing; type of research facility; time to complete study; and invasiveness, pain/discomfort, and possible side effects of procedures (all p < 0.05, d = 0.26-0.81). Differences in interest and willingness to participate in research probably contribute to different proportions of men and women as participants in exercise research. Knowledge of these differences might help researchers develop recruitment strategies aimed at encouraging both men and women to participate in exercise studies.

Muscle fatigue during maximal eccentric-only, concentric-only, and eccentric-concentric bicep curl exercise with automated drop setting.

Connected adaptive resistance exercise (CARE) machines are new technology purported to adjust resistance exercise loads in response to muscle fatigue. The present study examined muscle fatigue (strength loss, fatigue perceptions) during maximal eccentric-only (ECCmax -only), concentric-only (CONmax -only), and coupled ECC-CON (ECCmax -CONmax ) bicep curl exercise on a CARE machine. Eleven men and nine women completed the three protocols in separate sessions and in random order. All protocols included 4 sets of 20 maximal effort muscle contractions. Strength loss was calculated as Set 4 set end load minus Set 1 highest load. The CARE machine's algorithm adjusted resistances automatically, permitting continued maximal effort repetitions without stopping. Consequently, all protocols caused substantial fatigue. Women were most susceptible to strength loss from exercise that included maximal efforts in the ECC phase, whereas men were most susceptible to strength loss from exercise that included maximal efforts in the CON phase. With ECCmax -only exercise, ECC strength loss (mean ± SD) was similar between men (55.9 ± 14.1%) and women (56.4 ± 10.8%). However, with CONmax -only exercise, men and women experienced 55.6 ± 6.2% and 35.3 ± 8.7% CON strength loss, respectively. With ECCmax -CONmax exercise, men experienced greater ECC (62.9 ± 7.7%) and CON (77.0 ± 5.3%) strength loss than women (ECC: 48.5 ± 15.7%, CON: 66.2 ± 12.1%). Heightened perceptions of fatigue and pain of the exercised limb were reported after all protocols. Women generally reported more biceps pain than men. The results illustrate CARE technology delivers ECC-only and accentuated ECC exercise feasibly. Acute responses to repeated maximal effort bicep curl exercise with such technology might differ between men and women depending on muscle contraction type.

Overview of muscle fatigue differences between maximal eccentric and concentric resistance exercise.

Since the 1970s, researchers have studied a potential difference in muscle fatigue (acute strength loss) between maximal eccentric (ECCmax ) and concentric (CONmax ) resistance exercise. However, a clear answer to whether such a difference exists has not been established. Therefore, the aim of our paper was to overview methods and results of studies that compared acute changes in muscle strength after bouts of ECCmax and CONmax resistance exercise. We identified 30 relevant studies. Participants were typically healthy men aged 20-40 years. Exercise usually consisted of 40-100 isokinetic ECCmax and CONmax repetitions of the knee extensors or elbow flexors. Both ECCmax and CONmax exercise caused significant strength loss, which plateaued and rarely exceeded 60% of baseline, suggesting strength preservation. In upper-body muscles, strength loss at the end of ECCmax (31.4 ± 20.4%) and CONmax (33.6 ± 17.5%) exercise was similar, whereas in lower-body muscles, strength loss was less after ECCmax (13.3 ± 12.2%) than CONmax (39.7 ± 13.3%) exercise. Muscle architecture and daily use of lower-body muscles likely protects lower-body muscles from strength loss during ECCmax exercise. We also reviewed seven studies on muscle fatigue during coupled ECCmax -CONmax exercise and found similar strength loss in the ECC and CON phases. We also found evidence from three studies that more ECC than CON repetitions can be completed at equal relative loads. These results indicate that muscle fatigue may manifest differently between ECCmax and CONmax resistance exercise. An implication of the results is that prescriptions of ECC resistance exercise for lower-body muscles should account for greater fatigue resilience of these muscles compared to upper-body muscles.

Muscle strength and activity in men and women performing maximal effort biceps curl exercise on a new machine that automates eccentric overload and drop setting.

PURPOSE: Connected adaptive resistance exercise (CARE) machines are new equipment purported to adjust resistances within and between repetitions to make eccentric (ECC) overload and drop sets more feasible. Here, we examined muscle strength, endurance, electromyographic activity (EMG), and perceptions of fatigue during unilateral bicep curl exercise with a CARE machine and dumbbells. We also tested for sex differences in muscle fatigability. METHODS: Twelve men and nine women attempted 25 consecutive coupled maximal ECC-concentric (CON) repetitions (ECCmax-CONmax) on a CARE machine. Participants also completed a CON one repetition maximum (1RM) and repetitions-to-failure tests with 60 and 80% 1RM dumbbells. RESULTS: Maximal strength on the CARE machine was greater during the ECC than CON phase, illustrating ECC overload (men: 27.1 ± 6.8, 14.7 ± 2.0 kg; women: 16.7 ± 4.7, 7.6 ± 1.4 kg). These maximal resistances demanded large neural drive. Biceps brachii EMG amplitude relative to CON dumbbell 1RM EMG was 140.1 ± 40.2% (ECC) and 96.7 ± 25.0% (CON) for men and 165.1 ± 61.1% (ECC) and 89.4 ± 20.4% (CON) for women. The machine's drop setting algorithm permitted 25 consecutive maximal effort repetitions without stopping. By comparison, participants completed fewer repetitions-to-failure with the submaximal dumbbells (e.g., 60%1RM-men: 12.3 ± 4.4; women: 15.6 ± 4.7 repetitions). By the 25th CARE repetition, participants reported heightened biceps fatigue (~ 8 of 10) and exhibited large decreases in ECC strength (men: 63.5 ± 11.6%; women: 44.1 ± 8.0%), CON strength (men: 77.5 ± 6.5%; women: 62.5 ± 12.8%), ECC EMG (men: 38.6 ± 20.4%; women: 26.2 ± 18.3%), and CON EMG (men: 36.8 ± 20.4%; women: 23.1 ± 18.4%). CONCLUSION: ECC overload and drop sets occurred automatically and feasibly with CARE technology and caused greater strength and EMG loss in men than 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.

Narrative Review of Sex Differences in Muscle Strength, Endurance, Activation, Size, Fiber Type, and Strength Training Participation Rates, Preferences, Motivations, Injuries, and Neuromuscular Adaptations.

ABSTRACT: Nuzzo, JL. Narrative review of sex differences in muscle strength, endurance, activation, size, fiber type, and strength training participation rates, preferences, motivations, injuries, and neuromuscular adaptations. J Strength Cond Res 37(2): 494-536, 2023-Biological sex and its relation with exercise participation and sports performance continue to be discussed. Here, the purpose was to inform such discussions by summarizing the literature on sex differences in numerous strength training-related variables and outcomes-muscle strength and endurance, muscle mass and size, muscle fiber type, muscle twitch forces, and voluntary activation; strength training participation rates, motivations, preferences, and practices; and injuries and changes in muscle size and strength with strength training. Male subjects become notably stronger than female subjects around age 15 years. In adults, sex differences in strength are more pronounced in upper-body than lower-body muscles and in concentric than eccentric contractions. Greater male than female strength is not because of higher voluntary activation but to greater muscle mass and type II fiber areas. Men participate in strength training more frequently than women. Men are motivated more by challenge, competition, social recognition, and a desire to increase muscle size and strength. Men also have greater preference for competitive, high-intensity, and upper-body exercise. Women are motivated more by improved attractiveness, muscle "toning," and body mass management. Women have greater preference for supervised and lower-body exercise. Intrasexual competition, mate selection, and the drive for muscularity are likely fundamental causes of exercise behaviors in men and women. Men and women increase muscle size and strength after weeks of strength training, but women experience greater relative strength improvements depending on age and muscle group. Men exhibit higher strength training injury rates. No sex difference exists in strength loss and muscle soreness after muscle-damaging exercise.

Content Analysis of Patent Applications for Strength Training Equipment Filed in the United States Before 1980.

ABSTRACT: Nuzzo, JL. Content analysis of patent applications for strength training equipment filed in the United States before 1980. J Strength Cond Res 35(10): 2952-2962, 2021-Strength training history is an emerging academic area. The aim of the current study was to describe quantitively the history of inventions for strength training equipment. Content analysis was conducted of patent applications for strength training equipment filed with the U.S. Patent and Trademark Office before 1980. Applications were identified using relevant keyword searches in Google Patents. A total of 551 patent applications were analyzed. The earliest application identified was filed in 1860. Applications never exceed 6 per year until 1961 after which applications increased substantially, with a peak of 54 in 1979. Men invented 98.7% of all strength training devices. Lloyd J. Lambert, Jr. was the most prolific inventor, with 10 inventions. Types of inventions included mobile units (34.5%), stationary machines (27.9%), dumbbells (16%), racks or benches (8.0%), barbells (6.7%), and Indian clubs (3.8%). Common features included seats or benches (18.7%), cable-pulley systems (15.1%), weight stacks (8.2%), weight trays (4.5%), and cams (2.2%). Common types of resistance included weights or plates (33.2%), springs (11.6%), friction (9.1%), elastic bands (5.3%), and hydraulic (3.8%). Proposed invention benefits included adjustable resistance (37.4%), inexpensive (36.1%), simple to use (32.8%), compact design or easy storage (27.0%), multiple exercise options (26.1%), safety and comfort (25.4%), effectiveness (23.6%), portability (20.5%), adjustable size (15.8%), sturdiness or durability (15.8%), home use (13.6%), and light weight (13.6%). Certain aspects of strength training equipment have evolved over time. However, overall purposes and benefits of inventions have remained constant (e.g., affordability, convenience, personalization, safety, and effectiveness).

Inconsistent Use of Resistance Exercise Names in Research Articles: A Brief Note.

ABSTRACT: Nuzzo, JL. Inconsistent use of resistance exercise names in research articles: a brief note. J Strength Cond Res 35(12): 3518-3520, 2021-Academic fields require standard nomenclature to communicate concepts effectively. Previous research has documented resistance training exercises are named inconsistently. This inconsistent use has been observed among fitness professionals and within resistance training textbooks. The purpose of the current note was to explore inconsistent use of resistance training exercise names in scientific articles. Keyword searches were performed in PubMed to identify articles that referred to 4 different resistance training exercises. The search was limited to titles and abstracts of articles published between 1960 and 2020. For exercise 1, "shoulder press," "overhead press," and "military press" were searched. For exercise 2, "arm curl," "bicep curl," and "biceps curl" were searched. For exercise 3, "hamstring curl," "leg curl," and "knee curl" were searched. For exercise 4, "calf raise" and "heel raise" were searched. For exercise 1, 114 articles included "shoulder press" in their title or abstract, 42 articles included "overhead press," and 45 articles included "military press." For exercise 2, 244 articles included "arm curl," 37 articles included "bicep curl," and 177 articles included "biceps curl." For exercise 3, 24 articles included "hamstring curl," 159 articles included "leg curl," and 7 articles included "knee curl." For exercise 4, 68 articles included "calf raise" and 154 articles included "heel raise." The results are evidence of inconsistent use of resistance training exercise names in scientific articles. A possible solution to inconsistent use of exercise names in research articles, educational texts, and clinical practice is a system that includes a standard exercise naming pattern and guidelines for communicating exercise names.

History of Strength Training Research in Man: An Inventory and Quantitative Overview of Studies Published in English Between 1894 and 1979.

ABSTRACT: Nuzzo, JL. History of strength training research in man: an inventory and quantitative overview of studies published in English between 1894 and 1979. J Strength Cond Res 35(5): 1425-1448, 2021-Limited scholarship exists on the history of strength training research. The current review advances existing qualitative and biographical work by inventorying all experimental studies and case reports published before 1980 on the effects of ≥1 week of strength training on human health and function. Data on authors, journals, citations, study samples, training interventions, study outcomes, and study themes were extracted and summarized. Three hundred thirty-nine strength training studies were published between 1894 and 1979. Studies included 14,575 subjects, with 10,350 undergoing strength training. Subjects were usually healthy (81.1% of articles), university students (51.0%), or aged 18-65 years (86.7%). Men comprised 70.0% of subjects. Interventions typically involved isoinertial only (64.6%) or isometric only (35.4%) training. Upper-body interventions were more common (35.4%) than lower-body interventions (27.4%). Duration and frequency of training were typically 4-8 weeks (55.3%) and 3 days per week (39.2%), respectively. Isometric maximal voluntary contractions (54.0%) and one repetition maximum (20.4%) were the most common muscle strength tests. Other common outcomes included limb girths (20.9%) and muscle endurance (19.5%). Common research themes were physiology (54.3%), physical fitness (28.9%), and injury/rehabilitation (20.4%). The 339 studies have been cited 21,996 times. Moritani and deVries' 1979 article on time course of neuromuscular adaptations is the most highly cited (1,815 citations). DeLorme (5 articles and 772 citations), Hellebrandt (4 articles and 402 citations), Rasch (9 articles and 318 citations), and Berger (12 articles and 1,293 citations) made the largest contributions. Research Quarterly published the most articles (27.4%). The history of strength training research is discussed in the context of the results.

Men's health in the United States: a national health paradox.

A health paradox exists in the United States. Men have worse health outcomes than women, but national offices exist for promoting women's but not men's health. Two factors that might contribute to this paradox are: underappreciation for the number of health issues that affect men more than women and unawareness that men's health receives less attention than women's health. Therefore, the aim of this article was to summarize the data related to these two factors. First, using mostly government data, an inventory of health issues that are more common in males than females was generated, with prevalence rates listed. Second, results from two new scientometric analyses are presented: (a) number of times "men's health" and "women's health" appeared in titles or abstracts of papers in PubMed from 1970 to 2018; and (b) number of journals currently indexed in MEDLINE that specialize in men's or women's health. The epidemiological data illustrate numerous health issues are more prevalent in men than women, and scientometric data reveal men's health has been given less attention as a distinct field of biomedical research than women's health. This information can help to educate legislators, health officials, journalists, and the general public about the current paradox surrounding men's health in the United States.

Elbow angle modulates corticospinal excitability to the resting biceps brachii at both spinal and supraspinal levels.

NEW FINDINGS: What is the central question of this study? Corticospinal excitability to biceps brachii is known to modulate according to upper-limb posture. Here, cervicomedullary stimulation was used to investigate potential spinal contributions to elbow angle-dependent changes in corticospinal excitability at rest. What is the main finding and its importance? At more extended elbow angles, biceps responses to cervicomedullary stimulation were decreased, whereas cortically evoked responses (normalized to cervicomedullary-evoked responses) were increased. Results suggest decreased spinal excitability but increased cortical excitability as the elbow is placed in a more extended position, an effect that is unlikely to be attributable to cutaneous stretch receptor activation. ABSTRACT: Corticospinal excitability to biceps brachii is known to modulate according to upper-limb posture. In study 1, our aim was to investigate potential spinal contributions to this modulation and the independent effect of elbow angle. Biceps responses to transcranial magnetic stimulation (motor evoked potentials; MEPs) and electrical cervicomedullary stimulation (cervicomedullary motor evoked potentials; CMEPs) were measured at five elbow angles ranging from full extension to 130 deg of flexion. In study 2, possible contributions of cutaneous stretch receptors to elbow angle-dependent excitability changes were investigated by eliciting MEPs and CMEPs in three conditions of skin stretch about the elbow (stretch to mimic full extension, no stretch or stretch to mimic flexion). Each study had 12 participants. Evoked potentials were acquired at rest, with participants seated, the shoulder flexed 90 deg and forearm supinated. The MEPs and CMEPs were normalized to maximal compound muscle action potentials. In study 1, as the elbow was moved to more extended positions, there were no changes in MEPs (P = 0.963), progressive decreases in CMEPs (P < 0.0001; CMEPs at 130 deg flexion ∼220% of full extension) and increases in the MEP/CMEP ratio (P = 0.019; MEP/CMEP at 130 deg flexion ∼20% of full extension). In study 2, there were no changes in MEPs (P = 0.830) or CMEPs (P = 0.209) between skin stretch conditions. Therefore, although results suggest a decrease in spinal and an increase in supraspinal excitability at more extended angles, the mechanism for these changes in corticospinal excitability to biceps is not cutaneous stretch receptor feedback.

Aerobic Exercise Reduces Pressure More Than Heat Pain Sensitivity in Healthy Adults.

OBJECTIVES: The hypoalgesic effects of exercise are well described, but there are conflicting findings for different modalities of pain; in particular for mechanical vs thermal noxious stimuli, which are the most commonly used in studies of exercise-induced hypoalgesia. The aims of this study were 1) to investigate the effect of aerobic exercise on pressure and heat pain thresholds that were well equated with regard to their temporal and spatial profile and 2) to identify whether changes in the excitability of nociceptive pathways-measured using laser-evoked potentials-accompany exercise-induced hypoalgesia. SUBJECTS: Sixteen healthy adults recruited from the University of New South Wales. METHODS: Pressure and heat pain thresholds and pain ratings to laser stimulation and laser-evoked potentials were measured before and after aerobic cycling exercise and an equivalent period of light activity. RESULTS: Pressure pain thresholds increased substantially after exercise (rectus femoris: 29.6%, d = 0.82, P < 0.001; tibialis anterior: 26.9%, d = 0.61, P < 0.001), whereas heat pain thresholds did not (tibialis anterior: 4.2%, d = 0.30, P = 0.27; foot: 0.44%, d = 0.02, P = 1). Laser-evoked potentials and laser heat pain ratings also changed minimally after exercise (d = -0.59 to 0.3, P > 0.06). CONCLUSIONS: This is the first investigation to compare the effects of exercise on pressure and heat pain using the same stimulation site and pattern. The results show that aerobic exercise reduces mechanical pain sensitivity more than thermal pain sensitivity.

Words and Patterns That Comprise Resistance Training Exercise Names.

Nuzzo, JL. Words and patterns that comprise resistance training exercise names. J Strength Cond Res 31(3): 826-830, 2017-Limited research exists on the language associated with resistance training. The purpose of this study was to identify the ways in which resistance training exercises are named. Names of 57 exercises were obtained from the National Strength and Conditioning Association's Exercise Technique Manual for Resistance Training. The analysis consisted of categorizing into themes all the words of the exercise names and then identifying naming patterns. Names of the 57 exercises were comprised 188 total words. Seven percent of the words described body position (e.g., "seated"), 1.1% described body position direction (e.g., "over"), 19.1% described a body part (e.g., "shoulder"), 1.1% were body part adjectives ("stiff"), 30.3% described action (e.g., "row"), 5.9% described action direction (e.g., "lateral"), 23.4% described equipment (e.g., "barbell"), 8% described equipment position (e.g., "incline"), and 4.3% were considered miscellaneous (e.g., "power"). Of the 57 exercise names, 22.8% contained a body position word, 3.5% contained a body position direction word, 54.4% contained a body part word, 3.5% contained a body part adjective word, 94.7% contained an action word, 19.3% contained an action direction word, 61.4% contained an equipment word, 26.3% contained an equipment position word, and 12.3% contained a miscellaneous word. These types of words were used inconsistently. Additionally, 35 different naming patterns were discovered among the 57 exercise names. Overall, the findings reveal that current strategies for naming exercises are inconsistent. The strength and conditioning field can use this information to move toward standardizing the way in which resistance training exercises are named.

Arm posture-dependent changes in corticospinal excitability are largely spinal in origin.

Biceps brachii motor evoked potentials (MEPs) from cortical stimulation are influenced by arm posture. We used subcortical stimulation of corticospinal axons to determine whether this postural effect is spinal in origin. While seated at rest, 12 subjects assumed several static arm postures, which varied in upper-arm (shoulder flexed, shoulder abducted, arm hanging to side) and forearm orientation (pronated, neutral, supinated). Transcranial magnetic stimulation over the contralateral motor cortex elicited MEPs in resting biceps and triceps brachii, and electrical stimulation of corticospinal tract axons at the cervicomedullary junction elicited cervicomedullary motor evoked potentials (CMEPs). MEPs and CMEPs were normalized to the maximal compound muscle action potential (Mmax). Responses in biceps were influenced by upper-arm and forearm orientation. For upper-arm orientation, biceps CMEPs were 68% smaller (P= 0.001), and biceps MEPs 31% smaller (P= 0.012), with the arm hanging to the side compared with when the shoulder was flexed. For forearm orientation, both biceps CMEPs and MEPs were 34% smaller (both P< 0.046) in pronation compared with supination. Responses in triceps were influenced by upper-arm, but not forearm, orientation. Triceps CMEPs were 46% smaller (P= 0.007) with the arm hanging to the side compared with when the shoulder was flexed. Triceps MEPs and biceps and triceps MEP/CMEP ratios were unaffected by arm posture. The novel finding is that arm posture-dependent changes in corticospinal excitability in humans are largely spinal in origin. An interplay of multiple reflex inputs to motoneurons likely explains the results.

Stability of biceps brachii MMax with one session of strength training.

INTRODUCTION: The maximal compound muscle action potential (Mmax ) of biceps brachii is altered by 1 session of strength training. We examined whether the number of training sets in a session plays a role in this effect. METHODS: Ten subjects completed 1 session of isometric strength training of the elbow flexors (2 sets, 75% maximal force with 1 arm; 12 sets with the other). Biceps Mmax was acquired in both arms before training, immediately after training, and every 5 min for 30 min. RESULTS: Mmax area was initially potentiated after 2 (7.2%) and 12 sets (13.6%) but returned to baseline within 5 min. CONCLUSIONS: Biceps Mmax is similarly affected by 2 and 12 sets of strength training. The overall effect is minimal compared with ∼25% depression reported after similar training in a different arm posture. Thus, changes in Mmax appear more dependent on training posture than number of training sets. Muscle Nerve 54: 791-793, 2016.

The National Football League Scouting Combine from 1999 to 2014: normative reference values and an examination of body mass normalization techniques.

The primary purpose of this study was to identify the most appropriate method for normalizing physical performance measures to body mass in American football players. Data were obtained from the population of players (n = 4,603) that completed the vertical jump, broad jump, 40-yd sprint, 20-yd shuttle, 3-cone drill, and bench press at the National Football League Scouting Combine from 1999 to 2014. Correlation coefficients were used to assess relationships between body mass and physical performance measures. For the entire group and each playing position, absolute (i.e., non-normalized) performance measures were significantly (p ≤ 0.05) correlated with body mass, indicating that normalization is warranted. Ratio scaling, however, was not appropriate for normalizing most performance measures because it merely reversed (and increased in magnitude) the significant correlations between body mass and performance. Allometric scaling with derived allometric parameters was appropriate for normalizing all performance measures because correlations between body mass and performance were near to zero and no longer statistically significant. However, the derived allometric parameters differed by playing position. Thus, when normalizing physical performance measures to body mass, strength and conditioning professionals should use allometric scaling with test- and position-specific allometric parameters. Additionally, in the current study, percentile rankings were generated to provide test- and position-specific normative reference values for the absolute measures. Until body mass normalization techniques are adopted more broadly, strength and conditioning professionals can use these normative references values to compare current players with those who have already participated in the Scouting Combine.

Maximal Number of Repetitions at Percentages of the One Repetition Maximum: A Meta-Regression and Moderator Analysis of Sex, Age, Training Status, and Exercise.

The maximal number of repetitions that can be completed at various percentages of the one repetition maximum (1RM) [REPS ~ %1RM relationship] is foundational knowledge in resistance exercise programming. The current REPS ~ %1RM relationship is based on few studies and has not incorporated uncertainty into estimations or accounted for between-individuals variation. Therefore, we conducted a meta-regression to estimate the mean and between-individuals standard deviation of the number of repetitions that can be completed at various percentages of 1RM. We also explored if the REPS ~ %1RM relationship is moderated by sex, age, training status, and/or exercise. A total of 952 repetitions-to-failure tests, completed by 7289 individuals in 452 groups from 269 studies, were identified. Study groups were predominantly male (66%), healthy (97%), < 59 years of age (92%), and resistance trained (60%). The bench press (42%) and leg press (14%) were the most commonly studied exercises. The REPS ~ %1RM relationship for mean repetitions and standard deviation of repetitions were best described using natural cubic splines and a linear model, respectively, with mean and standard deviation for repetitions decreasing with increasing %1RM. More repetitions were evident in the leg press than bench press across the loading spectrum, thus separate REPS ~ %1RM tables were developed for these two exercises. Analysis of moderators suggested little influences of sex, age, or training status on the REPS ~ %1RM relationship, thus the general main model REPS ~ %1RM table can be applied to all individuals and to all exercises other than the bench press and leg press. More data are needed to develop REPS ~ %1RM tables for other exercises.