Do physiological measures predict selected CrossFit(®) benchmark performance?

Physiological differences between advanced CrossFit athletes, recreational CrossFit participants, and physically-active adults

This investigation examined anthropometric, hormonal, and physiological differences between advanced (ADV; n = 8, 27.8 ± 4.2 years, 170 ± 11 cm, 79.8 ± 13.3 kg) and recreational (REC; n = 8, 33.5 ± 8.1 years, 172 ± 14 cm, 76.3 ± 19.5 kg) CrossFit (CF) trained participants in comparison to physically-active controls (CON; n = 7, 27.5 ± 6.7 years, 171 ± 14 cm, 74.5 ± 14.3 kg). ADV and REC were distinguished by their past competitive success. REC and CON were resistance-trained (>2 years) and exercised on 3-5 days·wk-1 for the past year, but CON utilized traditional resistance and cardiovascular exercise. All participants provided a fasted, resting blood sample and completed assessments of resting metabolic rate, body composition, muscle morphology, isometric mid-thigh pull strength, peak aerobic capacity, and a 3-minute maximal cycle ergometer sprint across two separate occasions (separated by 3-7 days). Blood samples were analyzed for testosterone, cortisol, and insulin-like growth factor-1. Compared to both REC and CON, one-way analysis of variance revealed ADV to possess lower body fat percentage (6.7-8.3%, p = 0.007), greater bone and non-bone lean mass (12.5-26.8%, p ≤ 0.028), muscle morphology characteristics (14.2-59.9%, p < 0.05), isometric strength characteristics (15.4-41.8%, p < 0.05), peak aerobic capacity (18.8-19.1%, p = 0.002), and 3-minute cycling performance (15.4-51.1%, p ≤ 0.023). No differences were seen between REC and CON, or between all groups for resting metabolic rate or hormone concentrations. These data suggest ADV possess several physiological advantages over REC and CON, whereas similar physiological characteristics were present in individuals who have been regularly participating in either CF or resistance and cardiovascular training for the past year.

Prediction of competition performance via selected strength-power tests in junior weightlifters

BACKGROUND

Previous studies were limited to physical measurements or included very few performance test batteries, which has hindered the determination of the best tests for predicting competition performance in weightlifters. This study aimed to examine the relationships between body composition, Wingate anaerobic power, vertical jump height, isokinetic strength, handgrip strength, trunk strength, and competition performance and to determine the best predictors of competition performance in male junior weightlifters.

METHODS

Sixty-seven male junior weightlifters (age 16.6±1.5 years, height 166.6±5.2 cm, body mass 67.0±9.3 kg) voluntarily participated in this study. After a national weightlifting competition, the participants were evaluated for anthropometric measurements, Wingate anaerobic power, isokinetic strength, vertical jump, handgrip strength, and trunk strength tests. The competition performance of the participants was calculated using the Sinclair equation and used as the dependent variable in statistical analysis.

RESULTS

The correlations between the variables calculated from the five strength-power tests and the Sinclair score were significant (r=0.448 to 0.951, P≤0.05). The regression model suggested that the best predictors of weightlifting performance were Wingate mean power, the countermovement jump with arm swing, and body fat percentage, which accounted for approximately 88% of the common variance associated with competition performance in male junior weightlifters.

CONCLUSIONS

The results of this study showed that the predictors of weightlifting performance were Wingate mean power, countermovement jump with arm swing, and body fat percentage.

Part I: Crossfit-Related Injury Characteristics Presenting to Sports Medicine Clinic

OBJECTIVE

To investigate CrossFit-related injuries presenting to a pediatric sports medicine clinic.

DESIGN

Retrospective review of pediatric CrossFit-related injuries from between January 1, 2003, and June 31, 2016.

SETTING

Pediatric sports medicine clinic at a tertiary-level academic medical center.

PATIENTS

Patients with injury related to CrossFit participation.

INDEPENDENT VARIABLES

Sex, age, injury site, diagnosis, diagnostic imaging, and treatment.

MAIN OUTCOME MEASURES

Annual CrossFit-related injury proportion (%) over time.

RESULTS

One hundred fifteen medical identified (N = 55 female; mean age, 25.2 ± 10.4 years). Proportion of CrossFit-related injuries presenting to clinic relative to overall clinic volume consistently increased over time (Pearson r = 0.825; P = 0.022). Injury location included head (0.08%), trunk/spine (25.2%), upper extremity (27.0%), and lower extremity (47.0%). Common injured joints included knee (27%), spine (24.3%), and shoulder (16.5%). Nearly half of patients had a single diagnostic imaging (49.6%; 57 of 115). Most common diagnostics included magnetic resonance imaging (60.0%; 69 of 115), plain radiographs (51.3%; 59 of 115), ultrasound (10.4%; 12 of 115), and computerized tomographic scan (9.6%; 11 of 115). Most commonly prescribed treatments included physical/occupational therapy (38.3%; 44 of 115), activity modification (19.1%; 22 of 115), crutches/brace/splinting/compression sleeve (13.0%; 15 of 115), and non-steroidal anti-inflammatory medications (10.4%; 12 of 115).

CONCLUSIONS

CrossFit-related injury proportion presenting to a pediatric sports medicine clinic increased over time. A notable proportion of injuries occurred to the trunk and spine. Advanced imaging was obtained in approximately half of these youth athletes. Further research in youth CrossFit athletes is required surrounding mechanism of injury to prevent future injury in this mode of training for youth athletes.

Role of lactic acid on cognitive functions

Objectives: The aim of this research was to establish cognitive changes in relation to blood lactate levels obtained during slow performance of a regimen of exercise sessions. Methods: A total of 15 male professional bodybuilders participated in the study; CrossFit® professionals performed the Workout 15.5, Week 5 Open 2015 consisting of 27-21-15-9 repetitions for time of Row (calories) and Thrusters, with 1-min recovery. Blood lactate, blood glucose, reaction time (RT), execution time of a dual cognitive task, number of errors, and number of omissions were measured at rest, at conclusion of the session, and after recovery for 15 min. Results: The bodybuilders had slightly elevated basal lactate levels than in untrained individuals. The bodybuilders showed significantly increased lactacidemia and decreased RT after completing the training session. Need to define what onset of blood lactate accumulation (OBLA) means. Conclusion: We conclude that bodybuilding fitness regimens lead to an increase in basal lactate levels to 3.16 mmol/L and that acute training sessions can improve attentional performance in relation to lactacidemia, suggesting pro-cognitive effects of a workout.

48-hour recovery of biochemical parameters and physical performance after two modalities of CrossFit workouts

CrossFit is high-intensity interval training involving routines called 'workouts of the day' (WOD). The aim of the present study is to analyse biochemical parameters and physical performance after two modalities of CrossFit WODs, and to evaluate 48-hour recovery. Twelve trained CrossFit practitioners (age: 30.4 ± 5.37 years; VO2max: 47.8 ± 3.63 ml/min/kg; 1RM Power Clean: 93.2 ± 7.62 kg) participated in the study. A crossover design was applied, and participants completed two modalities of WODs on separate days: WOD1 (as many rounds as possible) and WOD2 (rounds for time). Blood lactate, ratings of perceived exertion and heart rate were measured to determine the intensity of training sessions. Biochemical parameters and physical performance were evaluated before, immediately after, 24 hours after and 48 hours after exercise. There were significant differences in intensity between WOD1 and WOD2 (lactate: 13.3±1.87 vs. 18.38±2.02 mmol/L, heart rate mean: 127.6±11.1 vs. 159.8±12.1 bpm), and blood glucose concentrations were significantly higher after WOD2 (135.4 ± 19.6 vs. 167.4±19.6 mg/dL). After exercise, WOD1 and WOD2 caused significant increases of hepatic transaminases, creatine phosphokinase and blood glucose, as well as a large decrease in the physical performance evaluated by the plank test. All these values returned to baseline by 48 hours after exercise. Both WODs caused metabolic and muscular stress, as well as a decrease in physical performance. All the levels recovered at 48 hours, so the stress caused by CrossFit WODs did not induce a pathological state.

The Effects of Acute Caffeine Supplementation on Performance in Trained CrossFit Athletes

Caffeine’s ergogenic effects persist during various exercise modalities; however, information establishing its efficacy during CrossFit protocols is limited. Our study aimed to determine the effects of caffeine supplementation on CrossFit performance. Thirteen CrossFit-trained men (age = 28.5 ± 6.6 years, experience = 49.2 ± 36.3 months) were randomized in a double-blind, crossover design. Participants completed two sessions separated by a seven-day washout period, 60 min after consuming 5 mg/kg body mass of caffeine or a placebo. In each session, participants completed as many rounds as possible in 20 min of 5 pull-ups, 10 push-ups, and 15 air squats. CrossFit performance was the total number of repetitions completed in 20 min. Paired samples t-tests were used to compare CrossFit performance between caffeine and placebo conditions and to test for a potential learning effect between the first and second sessions. CrossFit performance was significantly higher during the caffeine condition compared to the placebo (461.4 ± 103 vs. 425.0 ± 93.5 repetitions, p < 0.05). No significant learning effect was identified between the first and second sessions (445.6 ± 95.0 vs. 440.8 ± 105.0 repetitions, p = 0.73) nor was there a significant treatment order effect (p = 0.40). Caffeine’s ergogenic effect is present during CrossFit; however, future investigations should establish caffeine’s efficacy during other CrossFit protocols and among female athletes.

Physiological Performance Measures as Indicators of CrossFit® Performance

CrossFit^® began as another exercise program to improve physical fitness and has rapidly grown into the "sport of fitness". However, little is understood as to the physiological indicators that determine CrossFit^® sport performance. The purpose of this study was to determine which physiological performance measure was the greatest indicator of CrossFit^® workout performance. Male (n = 12) and female (n = 5) participants successfully completed a treadmill graded exercise test to measure maximal oxygen uptake (VO_2max), a 3-minute all-out running test (3MT) to determine critical speed (CS) and the finite capacity for running speeds above CS (D'), a Wingate anaerobic test (WAnT) to assess anaerobic peak and mean power, the CrossFit^® total to measure total body strength, as well as the CrossFit^® benchmark workouts: Fran, Grace, and Nancy. It was hypothesized that CS and total body strength would be the greatest indicators of CrossFit^® performance. Pearson's r correlations were used to determine the relationship of benchmark performance data and the physiological performance measures. For each benchmark-dependent variable, a stepwise linear regression was created using significant correlative data. For the workout Fran, back squat strength explained 42% of the variance. VO_2max explained 68% of the variance for the workout Nancy. Lastly, anaerobic peak power explained 57% of the variance for performance on the CrossFit^® total. In conclusion, results demonstrated select physiological performance variables may be used to predict CrossFit^® workout performance.

Functional high-intensity exercise training ameliorates insulin resistance and cardiometabolic risk factors in type 2 diabetes

NEW FINDINGS

What is the central question of this study? Does short-duration, high-intensity exercise training that combines functional aerobic and resistance exercises into training sessions lasting 8-20 min benefit individuals with type 2 diabetes? What is the main finding and its importance? Functional high-intensity training improves insulin sensitivity and reduces cardiometabolic risk in individuals with type 2 diabetes. This type of exercise training may be an effective exercise mode for managing type 2 diabetes. The increase in insulin sensitivity addresses a key defect in type 2 diabetes.

ABSTRACT

Functional high-intensity training (F-HIT) is a novel fitness paradigm that integrates simultaneous aerobic and resistance training in sets of constantly varied movements, based on real-world situational exercises, performed at high-intensity in workouts that range from ∼8 to 20 min per session. We hypothesized that F-HIT would be an effective exercise mode for reducing insulin resistance in type 2 diabetes (T2D). We recruited 13 overweight/obese adults (5 males, 8 females; 53 ± 7 years; BMI 34.5 ± 3.6 kg m^-2 , means ± SD) with T2D to participate in a 6-week (3 days week^-1 ) supervised F-HIT programme. An oral glucose tolerance test was used to derive measures of insulin sensitivity. F-HIT significantly reduced fat mass (43.8 ± 83.8 vs. 41.6 ± 7.9 kg; P < 0.01), diastolic blood pressure (80.2 ± 7.1 vs. 74.5 ± 5.8; P < 0.01), blood lipids (triglyceride and VLDL, both P < 0.05) and metabolic syndrome z-score (6.4 ± 4.5 vs. -0.2 ± 5.2 AU; P < 0.001), and increased basal fat oxidation (0.08 ± 0.03 vs. 0.10 ± 0.04 g min^-1 ; P = 0.05), and high molecular mass adiponectin (214.4 ± 88.9 vs. 288.8 ± 127.4 ng mL^-1 ; P < 0.01). Importantly, F-HIT also increased insulin sensitivity (0.037 ± 0.010 vs. 0.042 ± 0.010 AU; P < 0.05). Increases in high molecular mass adiponectin and basal fat oxidation correlated with the change in insulin sensitivity (ρ, 0.75, P < 0.05 and ρ, 0.81, P < 0.01, respectively). Compliance with the training programme was >95% and no injuries or adverse events were reported. These data suggest that F-HIT may be an effective exercise mode for managing T2D. The increase in insulin sensitivity addresses a key defect in T2D and is consistent with improvements observed after more traditional aerobic exercise programmes in overweight/obese adults with T2D.

High Intensity Functional Training (HIFT) and competitions: How motives differ by length of participation

High Intensity Functional Training (HIFT) is a unique fitness method that promotes an active lifestyle and has seen exponential and continual growth over the last two decades. Motivation to exercise is likely to change over time as individuals' motives to initiate exercise may be different than those which motivate them to maintain an exercise program. The purpose of this study was to examine the motivational factors reported by individuals who actively engage in HIFT with varying length of participation and competition levels. 737 adults (32.4 ± 8.2 years) with more than three-months of HIFT experience completed an online version of the Exercise Motivation Inventory (EMI-2) survey. Those who had greater length of participation reported more motives associated with relatedness (i.e., affiliation, competition) and enjoyment, while those with less HIFT participation were more motivated by body-related variables (i.e., weight management). Further, motivational variables (e.g., social recognition, affiliation, challenge) varied depending on whether or not individuals had competed in an online qualifier. Understanding these differences in motivation may aid in exercise promotion, initiation, and adherence, and moreover promote long-term physical and mental health benefits.

Self-reported Measures of Strength and Sport-Specific Skills Distinguish Ranking in an International Online Fitness Competition

Serafini, PR, Feito, Y, and Mangine, GT. Self-reported measures of strength and sport-specific skills distinguish ranking in an international online fitness competition. J Strength Cond Res 32(12): 3483-3493, 2018-To determine if self-reported performance measures could distinguish ranking during the 2016 CrossFit Open, data from 3,000 male (n = 1,500; 27.2 ± 8.4 years; 85.2 ± 7.9 kg; 177.0 ± 6.5 cm) and women (n = 1500, 28.7 ± 4.9 years; 63.7 ± 5.8 kg; 163.7 ± 6.6 cm) competitors was used for this study. Competitors were split by gender and grouped into quintiles (Q1-Q5) based upon their final ranking. Quintiles were compared for one-repetition maximum (1RM) squat, deadlift, clean and jerk (CJ), snatch, 400 m sprint, 5,000 m run, and benchmark workouts (Fran, Helen, Grace, Filthy-50, and Fight-Gone-Bad). Separate one-way analyses of variance revealed that all competitors in Q1 reported greater (p ≤ 0.05) 1RM loads for squat (men: 201.6 ± 19.1 kg; women: 126.1 ± 13.0 kg), deadlift (men: 232.4 ± 20.5 kg; women: 148.3 ± 14.5 kg), CJ (men: 148.9 ± 12.1 kg; women: 95.7 ± 8.4 kg), and snatch (men: 119.4 ± 10.9 kg; women 76.5 ± 7.6 kg) compared with other quintiles. In addition, men in Q1 (59.3 ± 5.9 seconds) reported faster (p ≤ 0.05) 400 m times than Q3 only (62.6 ± 7.3 seconds), but were not different from any group in the 5,000 m run. Women in Q2 (67.5 ± 8.8 seconds) reported faster (p ≤ 0.05) 400 m times than Q3-Q5 (73.5-74.8 seconds), and faster (21.3 ± 1.8 minutes, p < 0.02) 5,000 m times than Q4 (22.6 ± 2.2 minutes) and Q5 (22.6 ± 1.9 minutes). Faster (p ≤ 0.05) Fran times were reported by Q1 (men: 138.2 ± 13.3 seconds; women: 159.4 ± 28.3 seconds) compared with other groups, while the results of other workouts were variable. These data indicate that the most successful athletes excel in all areas of fitness/skill, while lower-ranking athletes should focus on developing strength and power after achieving sufficient proficiency in sport-specific skills.

Cardiometabolic and Muscular Fatigue Responses to Different CrossFit® Workouts

CrossFit® consists of workouts of the day (WODs) in which different exercises are conducted at high intensity with minimal or no rest periods. This study sought to quantify exercise intensity and muscular fatigue in the three CrossFit® session modalities: gymnastics (G), metabolic conditioning (M) and weightlifting (W). Thirty two, young, strength-trained, healthy men completed the three WODs: G ("Cindy"), M (double skip rope jumps) and W (power cleans). The variables measured in the sessions were: mean heart rate (HR), rate of perceived exertion (RPE), blood lactate [lactate], and jump height (H), average power (AP) and maximum take-off velocity (V_max) in a counter movement jump test. In all three WODs, elevated HR values (≥90% of the theoretical HR_max) were recorded at the time points mid-session and end-session. Mean RPEs were 17.6 ± 1.6 (G WOD), 16.0 ± 2.3 (M WOD), and 15.7 ± 2.0 (W WOD). Postexercise [lactate] was higher than 10 mmol·L^-1 for the three WODs. Following the G ("Cindy") and W (power cleans) WODs, respectively, significant muscular power losses were observed in H (7.3% and 8.1%), V_max (13.8% and 3.3%), AP relative (4.6% and 8.3%) and AP total (4.2% and 8.2%) while losses in the M WOD were not significant (p > 0.05). A vigorous intensity of exercise was noted in all three WODs, with greater mean HRs detected in the "Cindy" and skip rope WODs than power clean WOD. Muscular fatigue was produced in response to the "Cindy" and power clean WODs but not the skip rope WOD.

Repeated anaerobic tests predict performance among a group of advanced CrossFit-trained athletes

High-intensity functional training (HIFT) (i.e., CrossFit (CF) training) uses a combination of movements and self-selected time periods of work and rest. However, little is known about the physiological responses to an acute bout of HIFT exercise or about the physical parameters that distinguish performance. The purpose of this study was to examine the physiological responses in advanced CF athletes to consecutive Wingate trials with short, active recovery periods. Twenty-nine advanced-level CF-trained athletes volunteered for this study. The participants were required to complete 4 consecutive Wingate anaerobic tests (WAnTs) and a 15-min CF-style workout. Across the 4 WAnT trials, significant (p < 0.001) changes were observed in oxygen consumption, respiratory exchange ratio, and heart rate. Significant (p ≤ 0.001) differences among WAnT trials were observed in all anaerobic performance measures. Compared with all other trials, greater peak power (p < 0.04), relative peak power (p < 0.02), average power (p < 0.001), relative average power (p < 0.001), and total work (p < 0.001), together with a lower fatigue index (p < 0.01), were observed during WAnT 1. Overall, the 4 consecutive WAnT trials resulted in a significant (F = 177.0, p < 0.001) increase in blood lactate response. Stepwise regression revealed that the ability to predict total repetitions completed during the 15-min trial to complete as many repetitions as possible improved as the participants progressed from the first to the third WAnT trial. Our data suggest that, combined with the ability to better maintain performance across high-intensity exercise bouts, the ability to quickly recover between bouts is the most important factor in CF performance.

Normative Values for Self-Reported Benchmark Workout Scores in CrossFit® Practitioners

Background

CrossFit® practitioners commonly track progress by monitoring their ability to complete a variety of standardized benchmark workouts within a typical class setting. However, objective assessment of progress is challenging because normative data does not currently exist for any of these benchmark workouts. Therefore, the purpose of this study was to develop normative values for five common benchmark workouts (i.e., Fran, Grace, Helen, Filthy-50 [F50], and Fight-Gone-Bad [FGB]).

Methods

Performance data from 133,857 male (_M) and female (_F) profiles located on a publicly available website were collected and sorted by sex (i.e., male [_M] and female [_F]) and competitive age classification (i.e., teen [T], individual [I], or masters [M]) and screened for errors. Subsequently, 10,000 valid profiles were randomly selected for analysis.

Results

Means and standard deviations were calculated for each category for Fran (I_M 250 ± 106 s; I_F 331 ± 181 s; M_M 311 ± 138 s; M_F 368 ± 138 s; T_M 316 ± 136 s; and T_F 334 ± 120 s), Grace (I_M 180 ± 90 s; I_F 213 ± 96 s; M_M 213 ± 93 s; M_F 238 ± 100 s; T_M 228 ± 63 s; and T_F 223 ± 69 s), Helen (I_M 9.5 ± 1.9 min; I_F 11.1 ± 2.4 min; M_M 10.2 ± 2.0 min; M_F 11.5 ± 2.3 min; T_M 9.4 ± 1.6 min; and T_F 12.7 ± 1.9 min), F50 (I_M 24.4 ± 5.9 min; I_F 27.3 ± 6.9 min; M_M 26.7 ± 6.1 min; M_F 28.2 ± 6.0 min; T_M 25.9 ± 7.9 min; and T_F 28.3 ± 8.1 min), and FGB (I_M 335 ± 65 repetitions; I_F 292 ± 62 repetitions; M_M 311 ± 59 repetitions; M_F 280 ± 54 repetitions; T_M 279 ± 44 repetitions; and T_F 238 ± 35 repetitions). These values were then used to calculate normative percentile (in deciles) values for each category within each workout. Separate, one-way analyses of variance revealed significant (p < 0.05) differences between categories for each workout.

Conclusions

These normative values can be used to assess proficiency and sport-specific progress, establish realistic training goals, and for standard inclusion/exclusion criteria for future research in CrossFit® practitioners.

High-Intensity Functional Training (HIFT): Definition and Research Implications for Improved Fitness

High-intensity functional training (HIFT) is an exercise modality that emphasizes functional, multi-joint movements that can be modified to any fitness level and elicit greater muscle recruitment than more traditional exercise. As a relatively new training modality, HIFT is often compared to high-intensity interval training (HIIT), yet the two are distinct. HIIT exercise is characterized by relatively short bursts of repeated vigorous activity, interspersed by periods of rest or low-intensity exercise for recovery, while HIFT utilizes constantly varied functional exercises and various activity durations that may or may not incorporate rest. Over the last decade, studies evaluating the effectiveness of HIIT programs have documented improvements in metabolic and cardiorespiratory adaptations; however, less is known about the effects of HIFT. The purpose of this manuscript is to provide a working definition of HIFT and review the available literature regarding its use to improve metabolic and cardiorespiratory adaptations in strength and conditioning programs among various populations. Additionally, we aim to create a definition that is used in future publications to evaluate more effectively the future impact of this type of training on health and fitness outcomes.

Changes in body composition, bone metabolism, strength, and skill-specific performance resulting from 16-weeks of HIFT

High Intensity Functional Training (HIFT) is a training modality, characterized by multimodal exercises performed at high-intensity. Little is known about the training adaptations that occur as a prolonged training program. The purpose of this study was to examine changes in body composition, bone metabolism, strength, and skill-specific performance over 16-weeks of HIFT. Twenty-six recreationally active adult males (n = 9; 34.2 ± 9.1 y; 91.5 ± 17.7 kg; 178.5 ± 5.4 cm) and females (n = 17 = 36.4 ± 7.9 y; 91.5 ± 17.7 kg; 162.9 ± 7.0 cm) completed pre and post training assessments of body composition (Dual-Energy X-Ray Absorptiometry) and performance measures. Performance was assessed using three HIFT workouts (WOD 1-3) to assess strength, skill, and metabolic performance. Aside from the body composition measurements, all assessments were carried out at the local training facility. Training included participation in HIFT a minimum of twice a week for 16-weeks. Repeated measures analysis of variance revealed a significant gender x time interaction in Bone Mineral Content (BMC) (p = 0.027), where improvements favored women (1.0% ± 1.1%, p = 0.004) over men (-0.1% + 0.8%, p = 0.625). Further, region-specific analysis indicated that women (2.5% ± 3.0%, p < 0.005) experienced greater improvements in the trunk compared to men (-0.3% ± 1.8%, p = 0.621), while changes in leg BMC were comparable between women (0.8% ± 1.0%, p < 0.001) and men (0.3% ± 0.6%, p < 0.001). Although no other interactions were observed, significant performance improvements were noted for all participants in WOD 1 (18.3% ± 16.8%), absolute 5RM (14.4% ± 9.7%), relative 5RM (15.4% ± 9.2%), WOD 2 (5.7% ± 6.5%), and WOD 3 (-17.3% ± 14.7%). These data indicate that 16-weeks of HIFT resulted in positive outcomes in strength, metabolic conditioning performance, and body composition.

Are Changes in Physical Work Capacity Induced by High-Intensity Functional Training Related to Changes in Associated Physiologic Measures?

High-Intensity Functional Training (HIFT) is a novel exercise intervention that may test body systems in a balanced and integrated fashion by challenging individuals’ abilities to complete mechanical work. However, research has not previously determined if physical work capacity is unique to traditional physiologic measures of fitness. Twenty-five healthy men and women completed a six-week HIFT intervention with physical work capacity and various physiologic measures of fitness assessed pre- and post-intervention. At baseline, these physiologic measures of fitness (e.g., aerobic capacity) were significantly associated with physical work capacity and this relationship was even stronger at post-intervention assessment. Further, there were significant improvements across these physiologic measures in response to the delivered intervention. However, the change in these physiologic measures failed to predict the change in physical work capacity induced via HIFT. These findings point to the potential utility of HIFT as a unique challenge to individuals’ physiology beyond traditional resistance or aerobic training. Elucidating the translational impact of increasing work capacity via HIFT may be of great interest to health and fitness practitioners ranging from strength/conditioning coaches to physical therapists.

CrossFit Overview: Systematic Review and Meta-analysis

BACKGROUND

CrossFit is recognized as one of the fastest growing high-intensity functional training modes in the world. However, scientific data regarding the practice of CrossFit is sparse. Therefore, the objective of this study is to analyze the findings of scientific literature related to CrossFit via systematic review and meta-analysis.

METHODS

Systematic searches of the PubMed, Web of Science, Scopus, Bireme/MedLine, and SciELO online databases were conducted for articles reporting the effects of CrossFit training. The systematic review followed the PRISMA guidelines. The Oxford Levels of Evidence was used for all included articles, and only studies that investigated the effects of CrossFit as a training program were included in the meta-analysis. For the meta-analysis, effect sizes (ESs) with 95% confidence interval (CI) were calculated and heterogeneity was assessed using a random-effects model.

RESULTS

Thirty-one articles were included in the systematic review and four were included in the meta-analysis. However, only two studies had a high level of evidence at low risk of bias. Scientific literature related to CrossFit has reported on body composition, psycho-physiological parameters, musculoskeletal injury risk, life and health aspects, and psycho-social behavior. In the meta-analysis, significant results were not found for any variables.

CONCLUSIONS

The current scientific literature related to CrossFit has few studies with high level of evidence at low risk of bias. However, preliminary data has suggested that CrossFit practice is associated with higher levels of sense of community, satisfaction, and motivation.

Muscular fatigue in response to different modalities of CrossFit sessions

Background

CrossFit is a new strength and conditioning regimen involving short intense daily workouts called workouts of the day (WOD). This study assesses muscular fatigue levels induced by the three modalities of CrossFit WOD; gymnastics (G), metabolic conditioning (M) and weightlifting (W).

Material and methods

34 healthy subjects undertook three WOD (one per week): a G WOD consisting of completing the highest number of sets of 5 pull-ups, 10 push-ups and 15 air squats in 20 min; an M WOD, in which the maximum number of double skipping rope jumps was executed in 8 sets (20 s), resting (10 s) between sets; and finally, a W WOD in which the maximum number of power cleans was executed in 5 min, lifting a load equivalent to 40% of the individual's 1RM. Before and after each WOD, blood lactate concentrations were measured. Also, before, during, and after each WOD, muscular fatigue was assessed in a countermovement jump test (CMJ).

Results

Significant reductions were produced in the mechanical variables jump height, average power and maximum velocity in response to G; and in jump height, mean and peak power, maximum velocity and maximum force in response to W (P<0.01). However, in M, significant reductions in mechanical variables were observed between pre- and mid session (after sets 2, 4, 6 and 8), but not between pre- and post session.

Conclusions

Muscular fatigue, reflected by reduced CMJ variables, was produced following the G and W sessions, while recovery of this fatigue was observed at the end of M, likely attributable to rest intervals allowing for the recovery of phosphocreatine stores. Our findings also suggest that the high intensity and volume of exercise in G and W WODs could lead to reduced muscular-tendon stiffness causing a loss of jump ability, related here to a longer isometric phase during the CMJ.

Attentive processes, blood lactate and CrossFit®

OBJECTIVES

To analyze the influences of blood lactate produced during a specific session of CrossFit® on intensity and selectivity of attention. The first was evaluated by measuring the reaction time and the second by analyzing divided attention with a dual task.

METHODS

Fifteen male professionals of CrossFit® volunteered in the study. The training session was the Workout Of the Day (WOD) called 15.5, marked as: 27-21-15-9 repetitions (without recovery) in term of calories measured by using a rowing ergometer (e.g. 27 rowed calories) and in term of barbell full squats (raising a weight of 43 kg for men and of 29.5 kg for women). Blood lactate, blood glucose, reaction time, execution time of a dual task, number of errors and number of omissions were measured at rest, at the conclusion of the session and 15 minutes after its end.

RESULTS

The levels of the blood lactate before the start of the session were considerably higher than those which normally occur at rest (<2 mmol /L), with a mean value of 4.5 mmol /l (± 1.99 SD). At the end of the workout session the blood lactate exhibited a significant increase, reaching a mean value of 13.8 mmol /l (± 1.18 SD) and then returning to values similar to the initial ones after 15 minutes. Blood glucose did not exhibit any statistically significant differences during the session. Reaction time, execution time, number of errors and number of omissions exhibited a significant worsening concomitantly with the increase in blood lactate.

CONCLUSION

Athletes practicing CrossFit®, with high levels of blood lactate even at rest, should consequently have attentional performances somewhat limited.