Impact of Underwater Treadmill Training on Glycemic Control, Blood Lipids, and Health-Related Fitness in Adults With Type 2 Diabetes.

IN BRIEF A large number of adults with type 2 diabetes experience comorbidities that discourage physical activity and hinder regular participation in land-based exercise programs. An aquatic exercise program is an innovative exercise modality that incorporates combined aerobic and resistance exercise. The purpose of this study was to determine if an underwater treadmill walking program featuring gradual and progressive increases in walking speed and duration has a positive effect on glycemic control, metabolic health, cardiovascular function, body composition, and leg strength in middle-aged adults with type 2 diabetes.

Use of Functional Movement Screen Scores to Predict Dynamic Balance in Physically Active Men and Women.

Scudamore, EM, Stevens, SL, Fuller, DK, Coons, JM, and Morgan, DW. Use of functional movement screen scores to predict dynamic balance in physically active men and women. J Strength Cond Res 33(7): 1848-1854, 2019-The primary focus of this study was to determine whether scores obtained from the Functional Movement Screen (FMS) can predict dynamic balance in young, healthy adults. Thirty-four physically active participants completed the FMS, and balance was assessed using measures of composite reach (CR) distance and overall stability indices (OSI) derived from Y Balance and Biodex Balance System testing, respectively. Results indicated that higher overall FMS scores were associated with better CR and OSI, and participants with FMS composite scores greater than 14 exhibited better CR compared to those with composite scores less than or equal to 14. In addition, lasso penalized regression demonstrated that (a) scores of 2 on the deep squat and 3 on the trunk stability push-up movements predicted a greater CR and (b) higher shoulder mobility scores and a rotary stability score of 3 predicted better OSI. We conclude that dynamic balance in young, active men and women can be predicted by specific FMS item scores.

Effect of a rest-pause vs. traditional squat on electromyography and lifting volume in trained women.

PURPOSE: Rest-pause (4 s unloaded rest between repetitions) single session training effects on lifting volume, and muscle activity via electromyography (EMG) are currently vague in the literature and can benefit strength and conditioning professionals for resistance training program design. This study compared differences in volume lifted and muscle activity between a rest-pause vs. traditional protocol. METHODS: Trained females (N = 13) completed both a rest-pause and traditional squat protocol consisting of four sets to movement failure at 80% pretest 1 repetition maximum load with 2-min rest between sets. Total volume and muscle activity of the vastus lateralis, vastus medialis, rectus femoris, and gluteus maximus were measured on both training days. Differences in muscle activity were viewed as a percent change (%∆). RESULTS: A paired samples t test indicated total volume lifted was higher in the rest-pause compared to the traditional protocol (2532 vs. 2036 kg; p < .05). Furthermore, paired samples t tests showed muscle activity %∆ of the gluteus maximus was greater in the traditional protocol compared to the rest-pause protocol (p < .05). No other muscle activity differences were observed in the remaining muscles. CONCLUSIONS: The rest-pause allows for greater volume lifted via increased repetitions compared to a traditional protocol in trained women. The rest-pause method may be superior to a traditional method of training during a hypertrophy mesocycle, where a primary focus is total volume lifted. Furthermore, %∆ muscle activity in the GM will be greater while performing a traditional back squat protocol in comparison to a rest-pause.

An Evaluation of Time-Trial-Based Predictions of V[Combining Dot Above]O2max and Recommended Training Paces for Collegiate and Recreational Runners.

Scudamore, EM, Barry, VW, and Coons, JM. An Evaluation of time-trial-based predictions of V[Combining Dot Above]O2max and recommended training paces for collegiate and recreational runners. J Strength Cond Res 32(4): 1137-1143, 2018-The purpose of the current study was to determine the accuracy of Jack Daniels' VDOT Running Calculator for the prediction of V[Combining Dot Above]O2max, and recommendations of interval and training paces (pIN and pTH) in samples of National Collegiate Athletic Association Division 1 track athletes (ATH, n = 11) and recreational runners (REC; n = 9). Predicted variable data were obtained using results from indoor 5-km time-trials. Data from the VDOT Calculator were compared with laboratory-tested V[Combining Dot Above]O2max, pace at V[Combining Dot Above]O2max (V[Combining Dot Above]O2maxpace), and lactate threshold pace (LTpace). Results indicated that VDOT underestimated V[Combining Dot Above]O2max in ATH (t(10) = -6.00, p < 0.001, d = 1.75) and REC (t(8) = -8.96, p < 0.001, d = 3.44). Follow-up between-groups analysis indicated that the difference between VDOT and V[Combining Dot Above]O2max was significantly greater in REC than in ATH (p = 0.0031, d = 1.59). pIN was slower than V[Combining Dot Above]O2maxpace in REC (t(8) = -4.26, p = 0.003, d = 1.76), but not different in ATH (t(10) = 0.52, p = 0.614, d = 0.14). Conversely, pTH was faster than LTpace in ATH (t(8) = -4.17, p = 0.003, d = 1.49), but not different in REC (t(8) = 1.64, p = 0.139, d = 0.57). Practically, pTH can be confidently used for threshold training regardless of the ability level. pIN also seemed to be accurate for ATH, but may be not be optimal for improving V[Combining Dot Above]O2max in REC. Practitioners should interpret VDOT with caution as it may underestimate V[Combining Dot Above]O2max.

Muscle Activation Patterns of Lower-Body Musculature Among 3 Traditional Lower-Body Exercises in Trained Women.

Korak, JA, Paquette, MR, Fuller, DK, Caputo, JL, and Coons, JM. Muscle activation patterns of lower-body musculature among 3 traditional lower-body exercises in trained women. J Strength Cond Res 32(10): 2770-2775, 2018-The deadlift and back and front squats are common multijoint, lower-body resistance exercises that target similar musculature. To our knowledge, muscle activity measured using surface electromyography has never been analyzed among these 3 exercises. Furthermore, most literature examining this topic has included male participants creating a void in the literature for the female population. Knowledge of lower-body muscle activation among these 3 exercises can aid coaches, trainers, and therapists for training and rehabilitative purposes. Trained women (n = 13) completed 2 days of testing including a 1-repetition maximum (1RM) estimation, an actual 1RM, and 3 repetitions at 75% 1RM load for the deadlift and back and front squats. Muscle activity of the 3 repetitions of each muscle was averaged and normalized as a percentage to the 1RM lifts for the deadlift and front and back squats. Five separate repeated-measure analysis of variances were performed indicating muscle activity of the gluteus maximus (GM) differed among the 3 exercises (p = 0.01, (Equation is included in full-text article.)= 0.39). Specifically, post hoc analysis indicated greater muscle activity during the front squat (M = 94%, SD = 15%) compared with the deadlift (M = 72%, SD = 16%; p ≤ 0.05) in the GM. No significant differences were observed among the lifts in the vastus medialis, vastus lateralis, biceps femoris, and rectus femoris. Strength and conditioning specialist and trainers can use these findings by prescribing the front squat to recruit greater motor units of the GM.

Effect of rest-pause vs. traditional bench press training on muscle strength, electromyography, and lifting volume in randomized trial protocols.

PURPOSE: Rest-pause (4-s unloaded rest between repetitions) training effects on one repetition maximum (1 RM), lifting volume, and neural activation via electromyography (EMG) are currently vague in the literature and can benefit strength and conditioning professionals for resistance training programme design. Therefore, this study compared 1 RM, neural activation via (EMG), and volume differences between rest-pause vs. traditional resistance training. METHODS: Trained males (N = 20) were randomly assigned to either a rest-pause or a traditional training group. Pre- and post-1 RM testing was recorded. Training sessions were completed twice a week for 4 weeks and consisted of four sets of bench press to volitional fatigue at 80% of pre-test 1 RM with a 2-min rest between sets. Total volume completed was recorded on each training day. Neural activation of the pectoralis major was measured on the first and last training days. RESULTS: A two-way repeated-measures ANOVA indicated both groups significantly increased their 1 RMs following the 4-week training protocol (p < .05). However, no significant differences were found in 1 RM and neural activation between the two groups (p > .05). An independent samples t test indicated that total volume lifted was significantly higher for the rest-pause group (56,778 vs. 38,315 lbs; p < .05) throughout the protocol and independently during weeks 2, 3, and 4. CONCLUSIONS: While strength and neural activation changes did not differ between groups, both increased 1 RMs and the rest-pause group achieved greater increases in volume than the traditional group. If volume is the focus of training, the rest-pause method should be utilized.

Comparison of Running Economy Values While Wearing No Shoes, Minimal Shoes, and Normal Running Shoes.

Cochrum, RG, Connors, RT, Coons, JM, Fuller, DK, Morgan, DW, and Caputo, JL. Comparison of running economy values while wearing no shoes, minimal shoes, and normal running shoes. J Strength Cond Res 31(3): 595-601, 2017-The purpose of this study was to quantify differences in running economy (RE) at 50 and 70% of each subject's velocity at V[Combining Dot Above]O2max (vV[Combining Dot Above]O2max) across barefoot and 2 mass, stack height, and heel-to-toe-drop controlled footwear conditions (minimal shoes and normal running shoes) in 9 recreational distance runners (mean age 26.8 ± 6.8 years). Over 3 days, subjects ran in one of the footwear conditions while RE (oxygen consumption) and step frequency were measured at each speed with a 5-minute rest between each trial. A 2-way repeated-measures multivariate analysis of variance (p ≤ 0.05) and Bonferroni-adjusted follow-up analyses revealed that RE was not significantly different across footwear conditions at either speed. However, those running barefoot exhibited a higher step frequency than when running in minimal (50%, p = 0.007; and 70%, p < 0.001) and standard footwear conditions (70% only, p < 0.001). Higher step frequencies were also exhibited by those running in minimal versus standard footwear (70% only, p = 0.007). Thus, RE is not affected by footwear or running barefoot in those with experience running in minimal-type footwear. Significant adjustments in step frequency when alternative footwear was introduced may help explain why RE was statistically maintained during each footwear and speed condition across but not between subjects. Therefore, determination of footwear for the enhancement of RE should be based on individual physical characteristics and preferences rather than a global recommendation of an economical running shoe.

Comparisons of the airborne shuffle to standard walking while torso loaded.

The purpose of this study was to examine the effect of the airborne shuffle on oxygen cost (O2 cost), heart rate (HR), respiratory exchange ratio (RER), and stride length (SL) when compared with standard walking at 3 speeds (2.5, 3.0, and 3.5 mph) while torso loading. Twenty U.S. Army Reserve Officers' Training Course cadets (N = 20; age: 22 ± 3 years; height: 1.78 ± 0.08 m; body mass: 79.3 ± 10.7) participated in this study. At all speeds, the airborne shuffle had significantly higher O2 cost (p < 0.001), HR (p < 0.001), and RER (p < 0.001), and significantly shorter SL (p < 0.001) than walking. These findings suggest that using the airborne shuffle while torso loading is less economical and more likely to promote fatigue than walking. Therefore, the airborne shuffle is more likely to decrease performance on long marches than walking.

Caffeine supplementation and reactive agility in elite youth soccer players.

This study examined the effects of caffeine supplementation (6 mg·kg-1) on performance of a reactive agility test (RAT) in 17 elite, male, youth (M = 14 y) soccer players. Using a double-blind, repeated-measures design, players completed 4 days of testing on the RAT after a standardized warm-up. On day 1, anthropometric measurements were taken and players were accommodated to the RAT. On day 2, baseline performance was established. Caffeine or placebo conditions were randomly assigned on day 3 and the condition was reversed on day 4. Players completed 3 randomized trials of the RAT on days 2, 3, and 4 with at least 1 trial to the players' dominant and nondominant sides. There were no significant differences among conditions in reaction time (RT) to the dominant side, heart rates at any point of measurement, or ratings of perceived exertion (RPE) after completion of the warm-up. Caffeine produced faster RT to the nondominant side (P = .041) and higher RPE at the conclusion of the RAT (P = .013). The effect on the total time (TT) to complete the agility test to the nondominant side approached significance (P = .051). Sprint time and TT to either side did not differ. Caffeine supplementation may provide ergogenic benefit to elite, male, youth soccer players.

Live vs. digital video disk exercise in college--aged females.

Although exercise digital video disk (DVD) sales have substantially increased over the past decade, little is known on the effectiveness of personal training vs. DVD exercises. The purpose of this study was to compare energy expenditures and heart rates of live and DVD vigorously intense exercise sessions. Twenty active and low-to-moderate fit, college-aged females completed 2 identical exercise sessions. Each exercise session consisted of 6 exercises; 1 session was completed with a personal trainer and the other with a DVD. A portable metabolic analyzer was used to measure oxygen consumption and record heart rate. Both energy expenditure (p < 0.001) and heart rate (p = 0.001) were significantly higher during the live exercise session as compared with the DVD exercise session. Rate of perceived exertion was significantly higher for the live exercise session compared with the DVD exercise session (p = 0.045). Finally, the majority (89%) of the participants reported that they preferred the live exercise session over the DVD exercise session. The results suggest that low-to-moderately fit college-aged females not only prefer exercise sessions with a personal trainer but will also demonstrate higher energy expenditures and heart rates.

Effect of external load on muscle activation during the barbell back squat.

The aim of this study was to compare gluteus maximus-to-hamstring (GM:H) co-activation, hamstrings-to-quadriceps (H:Q) co-activation, and mean muscle activity in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RM), gluteus maximus (GM), semitendinosus (ST), and bicep femoris (BF) muscles across a range of training loads (40%, 50%, 50%, 70%, 80% 90% 1RM) of the barbell back squat in resistance trained females. Surface electromyography (EMG) was observed in 18 healthy resistance trained females for the VL, VM, RM, GM, ST, and BF during the ascending and descending phase of the back squat. During the ascending phase, the VL, VM, RM, GM, ST, and BF displayed significantly more EMG activation at 90% 1RM compared to 40%-70% (p < .03). During the descending phase, there were no significant differences displayed in mean muscle activity at 40%-80% of 1RM compared to 90% of 1RM. There were no significant differences in H-Q co-activation and GM-H co-activation during the ascending or descending phase across external loads. These findings are similar to the results found in similar studies using male participants and support that higher training intensities (80%-90% 1RM) of the barbell back squat significantly activate muscles surrounding the hip compared to lower loads (40%-70%). The results of this study also suggest that training intensities of 80% 1RM and 90% 1RM elicits the similar musculature activation in the muscle surrounding the hip in resistance trained females.HighlightsDuring the back squat, mean muscle activity of the hip and leg muscles increased linearly with exercise intensity (40%-90% of one-repetition max) in resistance trained females.No significant difference in mean activity were noted between 80% and 90% of one-repetition max during the ascending and descending phases.During the ascending phase, 80% of one-repetition max generated the highest gluteus maximus to hamstring activity co-activation ratio.During the descending phase, 40% of one-repetition max produced a gluteus maximus to hamstring activity co-activation ratio closest to 1.0.

Visual classification of running economy by distance running coaches.

AbstractObjectives: This study assessed the ability of coaches to rank-order distance runners on running economy (RE) through visual assessment. Methods: Running economy was measured in five trained recreational distance runners at a speed of 3.57 m·s-1, with a minimum VO2 difference of 2-mL.kg-1.min-1 between adjacent runners. Following measurement of RE, participants were filmed from the front, side, and rear while running on a treadmill. Endurance coaches from high school to international level (N = 121) viewed each video and ranked the runners on a scale from 1 (most economical) to 5 (least economical). Coaches also completed a demographic questionnaire and listed running style biomechanical observations they used in determining each ranking. A cumulative odds ordinal logistic regression with proportional odds was run to determine the effect of coaching level, years of coaching experience, years of training experience, competition level, certification status, and education level, on the ability of distance running coaching to accurately rank RE among a group of runners. Results: No coaching characteristic was a significant predictor of ranking accuracy, χ2 = 3.566, p = .735. Conclusions: Visual assessment of effort, based on RE, is a difficult task, even for the trained eye and could be related to difficulty in understanding the interaction effect of various RE factors or the translation of scientific-based knowledge to the field of play. Practically, coaches should be cautious when recommending biomechanical adjustments without considering the interconnected factors related to such changes.

Functional Movement Screen Items Predict Dynamic Balance Under Military Torso Load.

INTRODUCTION: Musculoskeletal injuries threaten military readiness and impose a significant financial burden. The functional movement screen (FMS), a 7-item, preparticipation screening tool, may aid in identifying compensatory movement patterns that can hinder physical performance and lead to injuries in active-duty military personnel. The primary aim of our study was to determine if items scores from the traditional FMS or a modified FMS (mFMS) obtained under loaded conditions can predict dynamic balance scores while wearing a military load. MATERIALS AND METHODS: Thirty physically active adults (19 males and 11 females) who qualified for Army basic training completed unloaded and loaded FMS testing. Loaded balance was assessed using the Y balance test and the Biodex balance system. The mFMS and both loaded balance assessment protocols included a military load consisting of a standard issue rucksack (M.O.L.L.E.), kevlar helmet, and weighted vest (mass = 24.2 kg). RESULTS: mFMS item scores were significantly lower than FMS scores for six of the seven movement items. Both FMS and mFMS composite scores were correlated with Y balance scores (FMS: r = 0.53, P = 0.003; mFMS: r = 0.37, P = 0.043). Participants with higher composite scores (≥15) outperformed those with lower composite scores (≤14) for the FMS (P =0.006, d = 1.16) and mFMS (P = 0.031, d = 0.75). Lasso penalized regression analyses revealed that (1) higher unloaded in-line lunge subscores predicted better Y balance scores, (2) loaded trunk stability push-up scores of three predicted worse balance on the Biodex, and (3) unloaded and loaded shoulder mobility scores of 3 predicted better performance on the Biodex balance system. CONCLUSIONS: The in-line lunge subscore from the FMS was the strongest predictor of torso-loaded balance, and the FMS may be more appropriate than a torso-loaded FMS battery when predicting torso-loaded balance among adults with body composition and fitness profiles similar to those of entering military recruits. These findings provide evidence supporting the use of the conventional FMS to identify active-duty personnel who exhibit greater balance deficits and may develop related musculoskeletal injuries while performing operational tasks that require the transport of heavy loads over long distances.

The effect of running barefoot and in barefoot-style footwear on running economy at two self-determined speeds.

BACKGROUND: The impact of barefoot running and footwear choice on running economy (RE; steady state oxygen consumption) is heavily debated. Therefore, this study measured RE when running barefoot versus two shod conditions. METHODS: Recreational male runners (N.=8) with experience running in both five-toed minimal (FTMS) and standard cushioned running shoes (SCRS), participated in RE trials while barefoot, FTMS, and SCRS for 5 minutes each trial at both 50% and 70% of speed at maximal oxygen uptake (sVO2max), while RE and step frequency (Sf) were measured. Separate one-way repeated measures ANOVAs were conducted for each footwear condition and each speed, on RE and Sf. RESULTS: No significant differences in RE were found at 50% or 70% sVO2max. Step frequency was significantly different at 70% sVO2max (F(2, 14)=6.74, P=0.009, partial ω2=0.06, as running barefoot (173.00±10.50 steps/min) exhibited a higher Sf than running in FTMS (68.81±10.94 steps/min; P=0.008) or SCRS (166.62±8.42 steps/min; P=0.044) conditions. CONCLUSIONS: No statistical RE benefit was found when running barefoot over FTMS or SCRS, possibly explained by a Sf adaptation at higher speeds. However, practically speaking, when shoe mass is controlled for, footwear choice has a moderate but worthwhile effect on RE. Consequently, formal familiarization and/or training in the FTMS may improve RE when compared to running in SCRS or barefoot in certain individuals.

Impact of EPOC adjustment on estimation of energy expenditure using activity monitors.

PURPOSE: To examine the accuracy of activity monitors in estimating energy expenditure (EE) during activities of varying mode and intensity and to evaluate the impact of including energy expended during recovery from activity (EPOC) on the EE estimate. EE estimates obtained from the Fitbit Surge (FBS), Garmin Vívofit (GV) and SenseWear Armband Mini (SWA) were compared to criterion EE with and without EPOC adjustments during moderate- and vigorous-intensity treadmill and cycling activities. METHODS: Participants (N = 34; 23 males) completed counterbalanced treadmill or cycling conditions, comprised of a resting metabolic rate measurement, 10-min bouts of moderate- and vigorous-intensity activity and an EPOC measurement. Participants simultaneously wore the three activity monitors and a portable metabolic analyser. RESULTS: The FBS provided lowest percent error (PE) during treadmill walking (4.4%) and the GV during moderate (6.4%) and vigorous (-0.1%) cycling bouts. EPOC-adjusted PE was higher than non-EPOC PE across all monitors and activities. Mean absolute error rate (MAPE), indicating overall measurement error, was the smallest for the FBS (14.1%) during moderate treadmill walking and the largest for the SWA (53.5%) for vigorous intensity cycling. Only the FBS had comparable non-EPOC (14.6%) and EPOC-adjusted (17.6%) MAPE during treadmill walking. CONCLUSION: The activity monitors tended to underestimate EE during moderate and vigorous treadmill and cycling activities. The EE estimates from the activity monitors did not account for the energy cost met by anaerobic means during activity, as suggested by the higher EPOC-adjusted EE error rates.