Transient Ischemic Attack in a 22-Year-Old NCAA Division I Baseball Athlete: A Case Study.

CONTEXT: A healthy, 22-year-old, male NCAA Division I baseball shortstop was experiencing confusion, chest pain, and tightness during an off-season intersquad scrimmage. The patient did not have any significant medical history or mechanism of head injury. After initial evaluation from the athletic trainer, the patient's cognitive status began to quickly decline. The emergency action plan was put in place rapidly and referred the patient to the local emergency clinic. CASE PRESENTATION: Upon arrival at the emergency department, an electrocardiogram was performed to rule out myocardial infarction or stroke. The first electrocardiogram results returned negative for any cardiac pathology, but a stroke alert was called. The patient was then transported to a level II trauma center due to continual cognitive decline. The patient was diagnosed with transient ischemic attack (TIA) secondary to an undiagnosed patent foramen ovale (PFO) that would later be diagnosed with further evaluation 2 months after the initial TIA incident. After multiple diagnostic and laboratory tests, the PFO went undetected until a 2D echocardiogram was performed and evaluated by a cardiologist. MANAGEMENT AND OUTCOMES: After the confirmation of the congenital defect, surgical intervention was performed to correct the PFO using catheterization. Despite multiple preparticipation examinations, electrocardiograms, and examination of past family history, the PFO went undetected until the patient experienced symptoms of TIA. The discovery of PFO in this 22-year-old athletic individual is unusual because traditional screening techniques (electrocardiogram and preparticipation examinations) failed to detect the congenital defect. CONCLUSIONS: Due to the emergent and timely actions of the athletic trainer, the patient has made a full recovery and is able to compete fully in athletic events. This case study amplifies the need for athletic trainers at all sporting events, updated and reviewed emergency action plans, rapid recognition of TIA in athletic individuals, and return-to-play protocol for an athletic individual after TIA.

Personal, Work-, and Client-Related Burnout Within Strength and Conditioning Coaches and Personal Trainers.

ABSTRACT: Snarr, RL and Beasley, VL. Personal, work-, and client-related burnout within strength and conditioning coaches and personal trainers. J Strength Cond Res 36(2): e31-e40, 2022-The purpose of this investigation was to examine the prevalence and influencing factors of personal, work-related, and client-related burnout within strength and conditioning coaches (SCCs) and personal trainers (PTs). Two hundred fifty-six SCCs (n = 141) and PTs (n = 115) completed the Copenhagen Burnout Inventory (CBI), a 19-item survey, measuring 3 subscales of personal, work-related, and client-related burnout. Information regarding other burnout-related factors (i.e., job satisfaction, social support, fitness level, and mental toughness) was solicited through single-item or multiple-item questionnaires. Correlational analyses and independent t-tests were conducted to assess associations and between-group differences between burnout and all continuous factors. Seventy-one subjects completed the survey before March 2020; after which, a worldwide pandemic (i.e., COVID-19) occurred possibly affecting employment workloads and work-related stress. Thus, post hoc analyses were conducted to assess differences in burnout scores pre-COVID-19 and post-COVID-19. Using a CBI subscale cutoff score of ≥50, fitness professionals reported 32.8% of personal burnout, 28.5% work-related burnout, and 18.0% client-related burnout. Factored by occupation, SCCs reported 32.6% personal burnout, 27.7% work-related burnout, and 18.4% client-related burnout. Within PTs, 33.0% reported personal burnout, 29.6% reported work-related burnout, and 17.4% reported client-related burnout. Higher levels of burnout, across all scales, were observed in those who were PTs, women, unmarried, living alone, would not choose to be a fitness professional again, and took the survey post-COVID as compared to their respective counterparts. Findings suggest that fitness professionals are not exempt from the stressors associated with personal and occupational burnout. Strength and conditioning coaches and PTs may reduce the risk of burnout by increasing social support, continuing education, and allowing for personal-care time with the intention of buffering these factors.

Seasonal Training Load Quantification and Comparison in College Male Soccer Players.

ABSTRACT: Ryan, GA, Snarr, RL, Eisenman, ML, and Rossi, SJ. Seasonal training load quantification and comparison in college male soccer players. J Strength Cond Res 36(4): 1038-1045, 2022-Monitoring and quantification of training load (TL) throughout a competitive soccer season is important to ensure players are able to perform throughout the season. The intent of this study was to examine the positional demands and patterns of select measures of TL during a 14-week season in collegiate male soccer players. Heart rate (HR), running performance (SZ), and perceived recovery data were collected daily using a bioharness for each subject (n = 21). Data were grouped into 2- to 3-week training blocks (Pre1, Pre2, In1, In2, In3, and In4). Continuous variables were analyzed using a multivariate analysis of variance, with post hoc Least Squared Difference pairwise comparisons. Significant positional differences were observed across the season. During Pre1, center midfielders (CM) spent more time in %HRlow compared to center backs (CB) (p < 0.01), wide midfielders (p < 0.01), and center forwards (p = 0.04). Center midfielders spent greater time in SZlower than CB (p < 0.01) and wide backs (WB) (p = 0.01). Wide backs spent greater time in SZupper compared to other positions (all p < 0.01). During Pre2, WB spent more time in %HRhigh and SZupper compared to other positions (all p < 0.01). Positional differences were more varied throughout in-season comparisons, but generally, WB and CB demonstrated higher intensities in variables compared to other positions. Tracking variations in positional TLs across the season is important for coaching and training staffs to determine player readiness and plan future training sessions, while helping to mitigate overuse injuries during a long competitive season.

V̇ o2 peak Comparison of a Treadmill Vs. Cycling Protocol in Elite Teenage Competitive Runners, Cyclists, and Swimmers.

ABSTRACT: Marko, D, Bahenský, P, Snarr, RL, and Malátová, R. V̇ o2 peak Comparison of a treadmill vs. cycling protocol in elite teenage competitive runners, cyclists, and swimmers. J Strength Cond Res 36(10): 2875-2882, 2022-The purpose of this study was to compare the cardiorespiratory and metabolic responses of a maximal graded exercise test (GXT) on a treadmill and cycle ergometer in elite-level, youth competitive athletes. Thirty-one athletes (11 distance runners, 11 mountain-bike cyclists, and 9 long-distance swimmers) were randomly selected to complete either a running or cycling GXT on the first day, followed by the alternative 72 hours apart. The initial work rate for each GXT was set at 50% of the individuals' previously established V̇ o2 peak to elicit fatigue within 8-12 minutes. For the treadmill protocol, speed was increased by 1 km·h -1 each minute, with a constant 5% grade, until volitional fatigue. Cycle ergometer work rate was increased by 30 W every minute until volitional fatigue or the inability to maintain proper cadence (i.e., 100 ± 5 rev·min -1 ). Throughout both testing sessions, V̇ o2 peak, heart rate [HR] peak, breathing frequency (BF), tidal volume (V T ), and minute ventilation (V E ) were assessed and used to compare within-sport differences. Runners displayed a higher V̇ o2 peak (∼7%; d = 0.92), HRpeak (4%; d = 0.77), V E (6%; d = 0.66), and BF (12%; d = 0.62) on the treadmill vs. cycle. However, the cycling group demonstrated a greater V̇ o2 peak (∼8%; d = 0.92), V T (∼14%; d = 0.99), and V E (∼9%; d = 0.78) on the cycle, despite no change in HRpeak. For swimmers, the treadmill GXT elicited higher values in V̇ o2 peak (∼5%; d = 0.75), BF (∼11.5%; d = 0.78), and HRpeak (3%; d = 0.69). Collectively, these findings indicate that exercise mode may greatly affect physiological outcome variables and should be considered before exercise prescription and athletic monitoring.

Relationship between pre-training wellness scores and internal and external training loads in a Division I women's lacrosse team.

This study examined the relationship between pre-training wellness scores and internal and external training load outputs during the preparation phase of a Division I women's collegiate lacrosse team. Athletes (n = 27) logged daily wellness (sleep, energy, stress, and how their muscles felt), session ratings of perceived exertion, and training metrics for 13 weeks. Load metrics were collected with microtechnology units. Repeated measures mixed linear models were constructed to evaluate the relationships between wellness and training load. The largest effects observed indicated: improved sleep was predictive of increased total distance (by as much as 310.5 m, 95%CI 36.7-584.3), high-intensity distance (by as much as 72.7 m, 95%CI 17.2-128.3), and Athlete Load (by as much as 6.8AU, 95%CI 1.8-11.8); more energy was predictive of increased total distance (by as much as 323.6 m, 95%CI 52.2-594.9) and Athlete Load (by as much as 5.6AU. 95%CI 0.6-10.5). For each one-unit increase in overall wellness score, total distance (3.5 m, 95%CI 1.2-15.1) and Athlete Load (0.2AU, 95%CI 0.0-0.3) increased. Pre-training wellness scores and sub-scores are predictive of external load training output. Monitoring athlete wellness systematically can help coaches with decision-making relevant to training and game performance.

Effect of Bench Press Load Knowledge on One Repetition Maximum Strength.

ABSTRACT: Snarr, RL, Adams, K, and Cook, J. Effect of bench press load knowledge on one repetition maximum strength. J Strength Cond Res 35(8): 2121-2126, 2021-Knowledge of a given load and visual feedback are crucial while performing a given task. Although previous literature has examined the consequences of lifting a submaximal weight, the removal of load knowledge has yet to be examined under maximal effort. Therefore, the purpose of this investigation was to examine the differences in 1 repetition maximum (1RM) bench press values between a known and unknown external load. Twenty resistance-trained subjects (10 male subjects and 10 female subjects) completed 2 trials of a 1RM bench press protocol separated by 48-72 hours. The two 1RM trials consisted of (a) a traditional 1RM lift in which subjects could see the external load and (b) a 1RM lift in which the external load was blocked from view of the subject. Trials were randomized for all subjects. Results indicated that no differences were observed when the load was known vs. unknown within all subjects (p = 0.094; Cohen's d = 0.03; intraclass correlation coefficient = 0.99). In addition, 40% decreased and 15% increased their 1RM, despite the unknown condition. A statistical difference was found between the initial 1RM estimation vs. measured 1RM during the known load trial (p = 0.034, Cohen's d = 0.07). Practitioners should note that load knowledge before a maximal lift does not appear to present any significant detrimental effects on performance. Therefore, training during a "blinded" condition may present a unique modality and additional balance component that would not be presented during a traditional maximal lift. Further examination of attentional focus and muscle activation differences are warranted.

Validity of Wearable Electromyographical Compression Shorts to Predict Lactate Threshold During Incremental Exercise in Healthy Subjects.

ABSTRACT: Snarr, RL, Tolusso, DV, Hallmark, AV, and Esco, MR. Validity of wearable electromyographical compression shorts to predict lactate threshold during incremental exercise in healthy subjects. J Strength Cond Res 35(3): 702-708, 2021-Determination of lactate threshold (LT) is an important variable in improving cardiovascular endurance and performance. Unfortunately, monitoring LT during exercise uses a costly, invasive blood analysis. Recently, electromyography (EMG) has been deemed a potential method of monitoring exercise intensity and may provide a noninvasive technique to monitor lactate during exercise. The purpose of this investigation was to determine if wearable surface EMG technology, acquired from specialized compression shorts, could estimate the LT work rate during incremental cycling. Thirteen men (n = 9) and women (n = 4) completed a maximal exercise test on a cycle ergometer. Blood lactate was measured every minute, whereas EMG was recorded throughout at the site of the vastus lateralis. Lactate and EMG thresholds were calculated using the Dmax method and compared using a Wilcoxon matched-pairs signed-rank test. Results demonstrated no significant differences between lactate and EMG thresholds in regards to work output (p = 0.83), percent maximal heart rate (p = 0.13; Cohen's d = 0.43), or percent peak oxygen consumption (p = 0.64; Cohen's d = 0.09). This confirms that both lactate and EMG exhibit similar properties (i.e., increasing exponential values) during incremental exercise. A possible mechanism includes the rise in blood lactate concentration, which increases motor unit recruitment in an attempt to maintain proper cadence and force output during incremental exercise. Thus, a coincidental, exponential increase in EMG amplitude may occur. Therefore, wearable EMG compression gear may provide a viable field tool for monitoring training intensity and predicting LT work rates.

Impact of Spotter Sex on One Repetition Maximum Bench Press Performance.

ABSTRACT: Nickerson, BS, Salinas, G, Garza, JM, Cho, S, and Snarr, RL. Impact of spotter sex on one repetition maximum bench press performance. J Strength Cond Res 35(9): 2397-2400, 2021-Resistance exercise is popular because of favorable health outcomes associated with increased muscular fitness. For these reasons, 1 repetition maximum (1RM), mean velocity (MV), and peak power (PP) are of interest during the bench press. However, research has yet to evaluate whether spotter sex impacts bench press performance. Therefore, the purpose of this study was to determine the impact of spotter sex on bench press performance during a 1RM testing protocol. Twenty resistance-trained individuals (10 men and 10 women) visited the laboratory on 2 separate occasions. Estimated 1RM was self-reported by subjects before the 1RM protocol. During their visits, subjects had their 1RM (kg), MV (m·s-1), and PP (W) determined on a bench press 1RM protocol while using a male or female spotter. Deception was used by telling subjects the intent of the study was to determine the reliability of a linear position transducer for measuring MV and PP during the 1RM trials. The main findings revealed that measured 1RM values for male weight lifters were significantly higher than estimated 1RM values when using both a male (p = 0.01) and female spotter (p < 0.01). In addition, results revealed MV and PP were significantly higher for the 1RM trials when male weight lifters had a male spotter (both p < 0.01). Alternatively, there were no significant differences in estimated vs. measured 1RM values for women as well as no effect of spotter sex on bench press strength (all p > 0.05). Practitioners should note that sex of a spotter does not seem to impact measured 1RM. However, notable influences may be observed within MV and PP.

Acute Effect of Popular High-Intensity Functional Training Exercise on Physiologic Markers of Growth.

ABSTRACT: Kliszczewicz, B, Markert, CD, Bechke, E, Williamson, C, Clemons, KN, Snarr, RL, and McKenzie, MJ. Acute effect of popular high-intensity functional training exercise on physiologic markers of growth. J Strength Cond Res 35(6): 1677-1684, 2021-Constantly evolving, high-intensity functional training (HIFT) exercise consists of various modalities, orders, weights, and repetition schemes. High-intensity functional training has gained popularity among the general population, but lacks empirical evidence regarding acute adaptive responses. The purpose of this study was to describe the acute effects of 2 representative bouts of HIFT on physiologic markers of growth. For convenience, the bouts are designated "short" (<5 minutes) and "long" (∼15 minutes), although duration was not the only difference between bouts. Ten apparently healthy men (28.1 ± 5 years) performed 2 HIFT bouts in a randomized crossover design. Blood was collected at 5 time points (Pre, Post, 1, 3, and 6 hours) to examine growth hormone (GH), insulin-like growth factor (IGF-1), insulin-like growth factor binding proteins 1 and 2 (IGFBP-1 and IGFBP-2), and vascular endothelial growth factor (VEGF). Blood lactate concentration ([La]) was analyzed at the Pre and Post time points. A repeated-measures analysis of variance (ANOVA) revealed no trial differences among the markers (IGF-1, IGFBP-1, IGFBP-2, and VEGF) except GH at Post, where the long bout produced a greater effect (p = 0.005). Mean GH levels (pg·ml-1) in the short bout increased from 68.4 to 106.5, and in the long bout, mean GH levels increased from 38.5 to 286.4. The repeated-measures ANOVA revealed a main time effect in GH (p = 0.037), while a post hoc t-test demonstrated elevated GH at 1 hour (p = 0.018) when compared with Pre. No time-dependent change (p > 0.05) was observed in IGF-1, IGFBP-1, IGFBP-2, or VEGF. Mean blood [lactate] increased more than tenfold in both bouts. The findings of this descriptive study suggest that, other than GH, there are no acute differences in markers of skeletal muscle or vascular growth between these 2 specific HIFT bouts.

The Relationship Between the National Football League Scouting Combine and Game Performance Over a 5-Year Period.

Cook, J, Ryan, GA, Snarr, RL, and Rossi, S. The relationship between the National Football League scouting Combine and game performance over a 5-year period. J Strength Cond Res 34(8): 2492-2499, 2020-There has been doubt on the ability of the National Football League (NFL) Scouting Combine to predict successful future game performance. This study analyzed data from athletes who participated in the Combine between 2013 and 2017 (n = 1,537) and their subsequent year's performance in the NFL. Data from 6 athletic measures were normalized for each athlete when compared with all other athletes (avgCZ) and athletes of the same position (avgPZ). Correlational analysis was used to ascertain whether the physical performance tests were associated with subsequent year's game performance (avgS). A multiple linear regression was performed to examine whether individual event Combine performance could predict the subsequent year's avgS in the NFL. Of the 35 correlations found when examining relationships, only 2 correlations were found to be moderately strong, avgCZ-avgS2 (r = 0.320), avgPZ-avgS2 (r = 0.332), whereas most were found to be weak (r < 0.3). Furthermore, data analysis suggests that Combine measures can only explain approximately 2.6% of the variance in avgS 1 year after the Combine when using 3 (vertical jump, bench press, and PRO) performance tests as predictors. The primary results of this study suggest that the NFL Combine lacks predictive ability when examining first year game performance. Furthermore, it also lacks correlational strength when examining relationships between performance and subsequent 5-year performance in the NFL. Caution should be used if coaches, general managers, and other front office staff are considering the use of Combine data as a possible selection for the upcoming NFL Draft.

Evaluation of Load-Velocity Relationships and Repetitions-to-Failure Equations in the Presence of Male and Female Spotters.

Nickerson, BS, Williams, TD, Snarr, RL, Garza, JM, and Salinas, G. Evaluation of load-velocity relationships and repetitions-to-failure equations in the presence of male and female spotters. J Strength Cond Res 34(9): 2427-2433, 2020-The purpose of this study was 2 fold: (a) to determine whether differences in mean concentric velocity (MCV), repetitions-to-failure (RTF), measured 1 repetition maximum (1RM), and 1RM prediction methods vary between lifter and spotter sex and (b) determine the accuracy of velocity-based 1RM (MCV1RM) and repetitions-to-failure-based 1RM (RTF1RM) prediction equations in the presence of either a male or female spotter. Twenty resistance-trained individuals (50% men) participated in this study. The initial 2 visits involved measuring 1RM for the bench press with a male or female spotter. Visits 3 and 4 required subjects to lift loads at 30 (5-repetitions), 50 (5-repetitions), and 70% 1RM (RTF) in the presence of a male or female spotter. Velocity-based 1RM was determined through individual regression equations using the submaximal loads (MCV30, MCV50, and MCV70). Repetitions-to-failure-based 1RM was determined through the RTF at 70% 1RM using Wathen (Wathen1RM), Mayhew (Mayhew1RM), and Epley (Epley1RM) equations. There were significant interactions when assessing Wathen1RM and Mayhew1RM (p < 0.05). Female lifters produced significantly higher estimated 1RM values during the male spotter condition using Wathen1RM and Mayhew1RM than the female spotter condition (p = 0.032 and 0.033, respectively). MCV1RM and Epley1RM produced smaller mean differences than Wathen1RM and Mayhew1RM when compared with measured 1RM. However, MCV1RM produced the largest standard error of estimate, whereas Epley1RM produced the lowest values. Epley1RM should be used over MCV1RM, Wathen1RM, and Mayhew1RM when loads up to 70% 1RM are implemented. Also, spotter sex only seems to impact female lifters when using the RTF1RM prediction equations of Wathen1RM and Mayhew1RM.

Validity of Foot-To-Foot Bioelectrical Impedance for Estimating Body Composition in NCAA Division I Male Athletes: A 3-Compartment Model Comparison.

Nickerson, BS, Snarr, RL, and Ryan, GA. Validity of foot-to-foot bioelectrical impedance for estimating body composition in NCAA Division I male athletes: A 3-compartment model comparison. J Strength Cond Res 33(12): 3361-3366, 2019-The purpose of this study was to validate single-frequency foot-to-foot bioelectrical impedance analysis (FF-BIA) against a 3-compartment (3C) model in NCAA Division I male athletes. Thirty-three athletes (football = 19, baseball = 8, basketball = 3, and cheerleading = 3) had body fat percentages (BF%) and fat-free mass (FFM) estimated using a 3C model and FF-BIA. The criterion 3C model was derived from body mass, body volume (air displacement plethysmography), and total body water (bioimpedance spectroscopy). The mean BF% and FFM values for FF-BIA were not statistically significant when compared with the 3C model (p = 0.14 and 0.28, respectively). The standard error of estimate (2.79% and 2.64 kg), total error (2.95% and 2.64 kg), and 95% limits of agreement (±5.67% and ±5.15 kg) were considered acceptable for BF% and FFM, respectively. However, there was a significant trend in the regression line of the Bland-Altman plot, which indicated proportional bias for BF% (r = -0.50; p < 0.01). No proportional bias was present for FFM (r = 0.26; p > 0.05). Foot-to-foot BIA seems to be valid for estimating group and individual athlete's FFM. Similarly, FF-BIA can be used for estimating group BF%. However, proportional bias indicates that FF-BIA is not valid for individual estimates of BF%.

Individual and Combined Effect of Inter-repetition Rest and Elastic Bands on Jumping Potentiation in Resistance-Trained Men.

Nickerson, BS, Williams, TD, Snarr, RL, and Park, K-S. Individual and combined effect of inter-repetition rest and elastic bands on jumping potentiation in resistance-trained men. J Strength Cond Res 33(8): 2087-2093, 2019-The purpose of this study was to determine the individual and combined effects of cluster sets (CS) and elastic bands for jumping potentiation in resistance-trained men. Twelve resistance-trained men (age: 22 ± 3 years) participated in this study. In a random order, participants completed 1 set of 3 repetitions at 85% 1-repetition maximum for the parallel back squat: (a) traditional set with continuous repetitions; (b) continuous repetitions with elastic bands (BANDS); (c) CS with 30 seconds of rest between each repetition (CS30); and (d) CS with 30 seconds of rest between each repetition and elastic bands (CS + BANDS). Vertical jump height (JH) and peak power (PP) were measured before exercise (baseline) and at 1, 4, 7, and 10 minutes after exercise for each condition. Results revealed that PP at 10 minutes was significantly higher than 7 minutes for BANDS (p = 0.035) and that 4 and 7minutes were both significantly higher than baseline for CS + BANDS (p = 0.008 and 0.031, respectively). No other differences were observed. There were medium effect sizes (ESs) for PP with BANDS (ES = 0.58 at 10 minutes), CS30 (ES = 0.53 and 0.64 at 7 and 10 minutes, respectively), and CS + BANDS (ES = 0.64, 0.78, and 0.66 at 4, 7, and 10 minutes, respectively). All remaining ES for JH and PP were trivial to small. Based on the moderate magnitude of effect, BANDS, CS30, and CS + BANDS were effective at potentiating vertical jump power. CS + BANDS is a more practical approach to potentiate vertical jump power when athletes are under strict time restraints.

Comparison of Lactate and Electromyographical Thresholds After an Exercise Bout.

Snarr, RL, Esco, MR, Tolusso, DV, Hallmark, AV, Earley, RL, Higginbotham, JC, Fedewa, MV, and Bishop, P. Comparison of lactate and electromyographical thresholds after an exercise bout. J Strength Cond Res 33(12): 3322-3331, 2019-The electromyographical threshold (EMGT) has been previously validated as a means to predict the work rate at which lactate threshold (LT) occurs. The reliability of these measures has yet to be examined after a bout of exercise. The purpose was to determine the agreement between electromyography (EMG) and LT after a 30-minute bout of steady-state aerobic exercise. Participants completed 2 graded exercise tests (GXT) on a cycle ergometer separated by 30 minutes of steady-state exercise. Blood lactate was measured the last 45 seconds of each stage during both GXTs, whereas EMG of the vastus lateralis was monitored continuously. Individual agreement demonstrated that pre-exercise and post-exercise LT occurred at the same work rate in 2 of 10 participants, whereas EMGT occurred at the same work rate in 6 of 10 participants. Results showed no mean difference between work rates for LT or EMG threshold for the pre-exercise GXT, but LT was significantly lower (p < 0.01) than EMGT during the post-exercise GXT. Post-GXT LT work rates were also determined to be significantly lower than pre-GXT LT (p = 0.034), whereas no differences existed in EMG thresholds. Although both LT and EMGT testing may display similar properties, they are not interchangeable. The physiological responses to increasing exercise intensity between La and EMG signaling seem to be associated, and their interaction may not be cause-effect. Because of poor individual agreement, caution should be used when determining LT through the use of EMG. Further research is needed to determine the ability of these 2 metrics to prescribe training intensities.

Cardiovascular and metabolic responses of active sitting while performing work-related tasks.

Stability balls and active-balance sitting chairs have recently emerged as a way to reduce sedentary behaviours in office settings. The purpose of this study was to determine differences in caloric expenditure and heart rate between a standard chair (SC), stability ball (SB) and active balanced sitting chair (ST) while performing work-related tasks. Participants (n = 20) performed a 10-minute randomised reading and typing task while sitting on the SC, SB and ST. For both the reading and typing tasks, heart rate (HR), caloric expenditure per minute and metabolic equivalents were all significantly greater (i.e. 6-13%; 19-40%; 18-39%, respectively) while using the ST when compared to the SC and SB. No significant differences were observed between the SB and SC for any of the comparisons. The ST produced a greater HR response and caloric expenditure than the SC or SB, indicating that active balanced sitting may be a feasible way to increase energy expenditure in an office setting. Practitioner summary: The purpose of this study was to determine differences in cardiovascular and metabolic responses to various forms of office chairs. The key finding was that active sitting on a balance chair significantly increased heart rate and caloric expenditure as compared to a stability ball and standard chair. Abbreviations: SC: standard chair; SB: stability ball; ST: active balanced chair; HR: heart rate; kcalmin: caloric expenditure per minute; MET: metabolic equivalents.

Validity of BMI-Based Body Fat Equations in Men and Women: A 4-Compartment Model Comparison.

Nickerson, BS, Esco, MR, Bishop, PA, Fedewa, MV, Snarr, RL, Kliszczewicz, BM, and Park, K-S. Validity of BMI-based body fat equations in men and women: a 4-compartment model comparison. J Strength Cond Res 32(1): 121-129, 2018-The purpose of this study was to compare body mass index (BMI)-based body fat percentage (BF%) equations and skinfolds with a 4-compartment (4C) model in men and women. One hundred thirty adults (63 women and 67 men) volunteered to participate (age = 23 ± 5 years). BMI was calculated as weight (kg) divided by height squared (m). BF% was predicted with the BMI-based equations of Jackson et al. (BMIJA), Deurenberg et al. (BMIDE), Gallagher et al. (BMIGA), Zanovec et al. (BMIZA), Womersley and Durnin (BMIWO), and from 7-site skinfolds using the generalized skinfold equation of Jackson et al. (SF7JP). The 4C model BF% was the criterion and derived from underwater weighing for body volume, dual-energy X-ray absorptiometry for bone mineral content, and bioimpedance spectroscopy for total body water. The constant error (CE) was not significantly different for BMIZA compared with the 4C model (p = 0.74, CE = -0.2%). However, BMIJA, BMIDE, BMIGA, and BMIWO produced significantly higher mean values than the 4C model (all p < 0.001, CEs = 1.8-3.2%), whereas SF7JP was significantly lower (p < 0.001, CE = -4.8%). The standard error of estimate ranged from 3.4 (SF7JP) to 6.4% (BMIJA) while the total error varied from 6.0 (SF7JP) to 7.3% (BMIJA). The 95% limits of agreement were the smallest for SF7JP (±7.2%) and widest for BMIJA (±13.5%). Although the BMI-based equations produced similar group mean values as the 4C model, SF7JP produced the smallest individual errors. Therefore, SF7JP is recommended over the BMI-based equations, but practitioners should consider the associated CE.

Electromyographical Comparison of Pike Variations Performed With and Without Instability Devices.

Snarr, RL, Hallmark, AV, Nickerson, BS, and Esco, MR. Electromyographical comparison of pike variations performed with and without instability devices. J Strength Cond Res 30(12): 3436-3442, 2016-Instability devices are primarily used with the intent of increasing the intensity of traditional exercises by providing further muscular demands of the abdominal wall by decreasing stability. Although there are multiple studies examining these devices, most often they only compare one such device to a stable movement and overlook the comparison among multiple devices. The purpose of this investigation was to compare the electromyographical differences of the rectus abdominis (RA), external oblique (EO), erector spinae (LSES), and rectus femoris (RF) during pike variations performed on various surfaces. Twenty men and women volunteered for this study. All subjects performed 5 variations of a pike on varying surfaces (i.e., stable ground [PK], Swiss ball [SB], suspension training device [ST], BOSU ball [BOSU], and Core Coaster [CC]). Normalized (%MVC) values were recorded for each muscle during 5 repetitions of each pike variations. For the RA, EO, LSES, and RF, the PK elicited significantly lower values compared with the instability devices. In terms of the EO, the ST was significantly higher than the BOSU, SB, and CC. Results of this investigation demonstrated significant differences between the instability devices and the stable pike. These results indicate that with more freely moving instability devices (e.g., suspension device, Swiss ball, etc.), core musculature may require greater muscular demands. Practitioners should take note that traditional stable pikes may not offer a core musculature challenge to resistance-trained individuals.

Cross-Validation of Age-Predicted Maximal Heart Rate Equations Among Female Collegiate Athletes.

The purpose of this study was to determine the accuracy of 3 general and 2 female-specific age-predicted maximal heart rate (HRmax) prediction equations in female collegiate athletes. Thirty female collegiate athletes (age = 21.5 ± 1.9 years, height = 164.7 ± 6.6 cm, weight = 61.3 ± 8.2 kg) participated. HRmax was determined with a maximal graded exercise test and predicted with 3 general equations (Fox et al., Astrand, and Tanaka et al.) and 2 female-specific equations (Fairbarn et al. and Gulati et al.). There was no significant difference between observed HRmax (185.9 ± 5.0 b·min) and the Fairbarn (187.5 ± 1.2 b·min) and Gulati (187.1 ± 1.7 b·min) equations (p = 0.11 and 0.23, respectively). The Fox (198.5 ± 1.9 b·min), Astrand (198.1 ± 1.6 b·min), and Tanaka (193.0 ± 1.4 b·min) equations provided significantly higher estimates compared with observed HRmax (p < 0.001 for each). The standard error of the estimate was similar for all the prediction equations (between 5.0 and 5.4 b·min), but the total error was smallest for Fairbarn and Gulati (5.3 b·min for each) and largest for Fox and Astrand (13.9 and 13.3 b·min, respectively). The 95% limits of agreement of the mean error were similar for all of the prediction equations, with values varying between 9.9 and 10.5 b·min. Because of the wide limits of agreement displayed by each equation, the use of age-predicted methods for estimating HRmax in collegiate female athletes should be performed only with caution.

Comparison of total and segmental body composition using DXA and multifrequency bioimpedance in collegiate female athletes.

The purpose of this investigation was to determine the agreement between multifrequency bioelectrical impedance analysis (BIA) and dual-energy x-ray absorptiometry (DXA) for measuring body fat percentage (BF%), fat-free mass (FFM), and total body and segmental lean soft tissue (LST) in collegiate female athletes. Forty-five female athletes (age = 21.2 ± 2.0 years, height = 166.1 ± 7.1 cm, weight = 62.6 ± 9.9 kg) participated in this study. Variables measured through BIA and DXA were as follows: BF%, FFM, and LST of the arms (ARMS(LST)), the legs (LEGS(LST)), the trunk (TRUNK(LST)), and the total body (TOTAL(LST)). Compared with the DXA, the InBody 720 provided significantly lower values for BF% (-3.3%, p < 0.001) and significantly higher values for FFM (2.1 kg, p < 0.001) with limits of agreement (1.96 SD of the mean difference) of ±5.6% for BF% and ±3.7 kg for FFM. No significant differences (p < 0.008) existed between the 2 devices (InBody 720-DXA) for ARMS(LST) (0.05 kg), TRUNK(LST) (0.14 kg), LEGS(LST) (-0.4 kg), and TOTAL(LST) (-0.21 kg). The limits of agreement were ±0.79 kg for ARMS(LST), ±2.62 kg for LEGS(LST), ±3.18 kg for TRUNK(LST), and ±4.23 kg for TOTAL(LST). This study found discrepancies in BF% and FFM between the 2 devices. However, the InBody 720 and DXA appeared to provide excellent agreement for measuring total body and segmental LST. Therefore, the InBody 720 may be a rapid noninvasive method to assess LST in female athletes when DXA is not available.

Monitoring changes in VO2max via the Polar FT40 in female collegiate soccer players.

This study was conducted to determine if the Polar FT40 could accurately track changes in maximal oxygen consumption (VO2max) in a group of female soccer players. Predicted VO2max (pVO2max) via the Polar FT40 and observed VO2max (aVO2max) from a maximal exercise test on a treadmill were determined for members of a collegiate soccer team (n = 20) before and following an 8-week endurance training protocol. Predicted (VO2max and aVO2max measures were compared at baseline and within 1 week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference in aVO2max (pre = 43.6 ± 2.4 ml · kg · min(-1), post = 46.2 ± 2.4 ml · kg · min(-1), P < 0.001) and pVO2max (pre = 47.3 ± 5.3 ml · kg · min(-1), post = 49.7 ± 6.2 ml · kg · min(-1), P = 0.009) following training. However, predicted values were significantly greater at each time point compared to observed values (P < 0.001 at pre and P = 0.008 at post). Furthermore, there was a weak correlation between the change in aVO2max and the change in pVO2max (r = 0.18, P = 0.45). The Polar FT40 does not appear to be a valid method for predicting changes in individual VO2max following 8 weeks of endurance training in female collegiate soccer players.