Measuring the attention networks and quantitative-electroencephalography correlates of attention in depression.

Given the association between major depressive disorder (MDD) and cortical inefficiency related to executive control, specifically in the sense that individuals with MDD may recruit more cognitive resources to complete tasks at the same capacity as those without MDD, the current study was interested in examining the attention networks and executive functioning of those with MDD. Past research has used the Attention Network Test (ANT) to measure changes of attention in clinical vs. healthy populations; however, theoretical concerns have been raised regarding the task. The Combined Attention Systems Task (CAST) was developed to address these concerns and was used in our study in combination with quantitative-electroencephalography (QEEG) to assess both behavioural and neurophysiological changes in participants with MDD (n = 18) compared to healthy controls (HCs; n = 22). We found no behavioural differences between MDD and HC groups suggesting individuals with MDD in our sample were not experiencing the executive functioning deficits previously reported in the literature. Neurophysiological measures of attention revealed that MDD participants had greater theta and alpha1 activity relative to HCs, suggesting that although individuals with MDD do not show deficits in behavioural attention, they exhibit altered neural processing which underlies cognitive function.

Effect of Load on Muscle Activity, Kinematics, and Force Production During the Reverse Hyperextension Exercise.

The reverse hyperextension exercise is used to strengthen posterior chain musculature without axially loading the spine; however, there are no suggestions for loading. Twenty recreationally active individuals (13 males and 7 females; aged 25.4 [2.5] y; height 1.76 [0.09] m; mass 79.3 [15.8] kg) performed 2 sets of 10 repetitions with 50%, 100%, and 150% of bodyweight. Surface electromyography measured erector spinae, gluteus maximus, and biceps femoris activity. Motions of the trunk, lower extremities, and reverse hyperextension exercise pendulum were tracked. A 1-way repeated-measures analysis of variance was used to analyze differences. Few differences were found between 100% and 150% loads; however, heavier loads resulted in increased hip (5.0°) and trunk (4.0°) flexion compared with the 50% load. Similar patterns emerged for peak and integrated muscle activity, with erector spinae and gluteus maximus activity greater in the 100% and 150% loads than in the 50% load, and biceps femoris activation increasing as load increased. Peak force significantly (P < .001) increased with 100% (28% [31%]) and 150% (34% [40%]) loads compared with the 50% load. Findings suggest the reverse hyperextension exercise targets posterior chain musculature, but increasing loads does not linearly increase force and muscle activation.

Effect of Unstable Loads on Stabilizing Muscles and Bar Motion During the Bench Press.

ABSTRACT: Lawrence, MA, Ostrowski, SJ, Leib, DJ, and Carlson, LA. Effect of unstable loads on stabilizing muscles and bar motion during the bench press. J Strength Cond Res 35(2S): S120-S126, 2021-Unstable loads are anecdotally used to increase muscle stabilizer strength and utilization; however, there is little evidence to support these claims. Twelve male powerlifters (age 28.6 ± 5.2 years, body mass 105.6 ± 14.5 kg, lifting experience 9.8 ± 6.0 years, and bench press 5 repetition maximum [5RM] 133.6 ± 30.9 kg) pressed their 5RM in one stable condition with a standard barbell, and 3 unstable conditions using a flexible barbell with weights suspended from elastic bands. Mean integrated muscle activity for each repetition of the stabilizers and prime movers were measured. A Lyapunov exponent and sample entropy indicated unstable loads were less predictable and more variable in the superior/inferior direction, thus more challenging to control, despite decreased loads. The main finding was increased bicep activity in all unstable conditions (light bands and plates, +57%; mini bands and plates, +67%; and mini bands and kettlebells, +88%). Although less weight was used in the unstable 5RMs, most stabilizer muscle activity was not different between conditions, suggesting that the amount of weight used during unstable load training (up to 32.3% less load) may be limited by the ability of stabilizer muscles to control the load.

Effects of Tibiofibular and Ankle Joint Manipulation on Hip Strength and Muscle Activation.

OBJECTIVES: The purpose of this study was to determine whether high-velocity, low-amplitude ankle region manipulations could increase force output and muscle activation of hip musculature in individuals with a history of ankle sprain and unilateral tensor fascia latae (TFL) weakness during muscle testing. METHODS: This investigation used a single-arm repeated measures design. Twenty-five participants' force outputs were tested at three time points (before manipulation, immediately after manipulation, and 48 hours after manipulation), and muscle activation of the rectus femoris, gluteus medius, and TFL was measured before and immediately after manipulation. Manipulations were applied to the talocrural, subtalar, proximal, and distal tibiofibular joints of the weaker limb. No contralateral manipulations were applied. Two-way repeated measures analysis of variance was used to compare maximal and average force production for each limb. In addition, paired t tests were used to compare muscle activation before and after manipulations. RESULTS: There was a significant limb × time interaction. The involved limb average force increased from before manipulation (65.7 N) to 48 hours after manipulation (77.8 N; P = .014), maximal force increased (76.9 N) 48 hours after manipulation (87.8 N; P = .030), and gluteus medius activation increased (9.8% maximum, 12.2% average) immediately after manipulation. No significant differences were found in the uninvolved limb. CONCLUSION: The results of this study suggest that high-velocity, low-amplitude ankle region manipulations might improve hip abductor strength in individuals with a history of ankle sprain and unilateral weakness during a TFL muscle test.

The Attention Network Test Database: ADHD and Cross-Cultural Applications.

Attention is a central component of cognitive and behavioral processes and plays a key role in basic and higher-level functioning. Posner's model of attention describes three components or networks of attention: the alerting, which involves high intensity states of arousal; the orienting, which involves the selective direction of attention; and the executive control, which involves cognitive functions such as conflict resolution and working memory. The Attention Network Test (ANT) is a computerized testing measure that was developed to measure these three networks of attention. This project describes the ANT, its widely used variants, and the recently developed ANT Database, a repository of data extracted from all studies that have used the ANT as of 2019. To illustrate the potential uses of the database, two meta-analyses conducted using the ANT Database are described. One explores task performance in children with and without attention deficit/hyperactivity disorder (ADHD). The other one explores regional differences between studies conducted in China, Europe, and the United States. We are currently in the process of integrating the database into a publicly available web interface. When that work is complete, researchers, clinicians, and the general public will be able to use the database to explore topics of interest related to attention.

Activity of Trunk and Lower Extremity Musculature: Comparison Between Parallel Back Squats and Belt Squats.

The back squat is widely used in strength training programs. Alternatively, the belt squat has been gaining popularity since it loads the weight on the hips, as opposed to the shoulders and spine. The purpose of this study was to determine whether using a belt squat would result in less lumbar extensor activation while providing similar excitation of other prime mover and stabilizer musculature. Ten participants (9 males, 1 female; age 29.3 ± 4.9 years; body mass 96.2 ± 17.8 kg) who regularly trained both belt squats and back squats performed three sets of 5 repetitions with 100% bodyweight for each exercise. Peak and integrated muscle activity was calculated and normalized to a maximum voluntary isometric contraction. A one-way ANOVA (p < 0.05) was used to compare conditions. Belt squatting decreased lumbar erector impulse (45.4%) and peak (52.0%) activation as compared to the back squat. Belt squatting did not alter activation of the lower extremities except for a decrease in the gluteus maximus (35.2% impulse and 32.1% peak), gluteus medius (54.1% impulse and 55.2% peak). Furthermore, belt squatting reduced activation of the rectus abdominus (44.3% impulse; 31.1% peak), and external obliques (45.8% impulse; 53.7% peak) as compared to back squatting. Our results suggest belt squatting provides similar muscular demands for the quadriceps, hamstrings, and plantar flexors, but is less demanding of trunk stabilizers, and gluteual muscles. Belt squats may be a suitable alternative to back squats in order to avoid stressing low back or trunk musculature.

Psychometric Properties of the Merrill-Palmer-Revised Scales of Development in Preschool Children With Autism Spectrum Disorder.

Psychometrically sound tests of intellectual ability are indispensable for research and assessment of children with autism spectrum disorder (ASD), yet few tests have been validated for use with this population. The Merrill-Palmer-Revised Scales of Development (M-P-R) is a standardized test of intellectual ability that was validated for use with typically developing preschoolers. The current study's aim was to investigate the criterion validity of the M-P-R for assessing cognitive skills in preschoolers with ASD (N = 180). Good concurrent validity was demonstrated, with a large positive correlation between the M-P-R Receptive Language domain and the PLS-4 Auditory Comprehension subscale. The Cognitive domain of the M-P-R showed a medium positive correlation with later WISC-4 scores, showing acceptable predictive validity. Cognitive strengths and weaknesses assessed using the M-P-R mirrored those described for other measures, with most children obtaining higher standard scores on the Cognitive than the Receptive Language domain. An exploratory factor analysis suggested that one factor accounted for the majority of variability in M-P-R domains.

Activity of Shoulder Stabilizers and Prime Movers During an Unstable Overhead Press.

Williams, MR Jr, Hendricks, DS, Dannen, MJ, Arnold, AM, and Lawrence, MA. Activity of shoulder stabilizers and prime movers during an unstable overhead press. J Strength Cond Res 34(1): 73-78, 2020-Overhead reaching is a common movement that relies heavily on muscles for dynamic stability. Stabilizer muscle activation increased during squatting and bench pressing with an unstable load, but the overhead press (OHP) has yet to be examined. The purpose of this study is to compare muscle activity of the shoulder stabilizers and prime movers and excursions of the center of pressure (CoP) during the OHP in 2 unstable and one stable conditions. Twelve men (aged 25.3 ± 2.7 years, mass: 91.5 ± 8.4 kg, height: 1.81 ± 0.06 m) pressed 50% of their 1 repetition maximum for 10 repetitions over 3 conditions: a straight stable barbell (SS), a straight unstable (SU) barbell with kettlebells suspend by elastic bands, and an unstable Earthquake (EU) bar with kettlebells suspended by elastic bands. Activity of the shoulder stabilizers and prime movers were measured via surface and indwelling electromyography. Center of pressure excursion of the right foot was also measured. A multivariate analysis was used to determine significant differences between conditions. Pressing with the EQ increased activation of the biceps brachii, erector spinae, latissimus dorsi, pectoralis major, rectus abdominus, rhomboids, and serratus anterior over the SS condition, whereas only the SU condition increased activation in the erector spinae and latissimus dorsi muscles. The EQ condition produced greater CoP excursion (35.3 ± 7.9% foot length) compared with the SU (28.0 ± 7.2% foot length) and SS (22.2 ± 6.3% foot length) conditions. Therefore, the EU condition may be an effective exercise to activate scapular stabilizers.

Using the locus of slack logic to determine whether the output form of inhibition of return affects an early or late stage of processing.

Slower reaction times to targets presented at a previously cued or attended location are often attributed to inhibition of return (IOR). It has been suggested that IOR affects a process at the output end of processing continuum when it is generated while the oculomotor system is activated. Following the path set by Kavyani, Farsi, Abdoli, and Klein (2017) we used the locus of slack logic embedded in the psychological refractory period (PRP) paradigm to test this idea. We generated what we expected would be the output form of IOR by beginning each with participants making a target directed saccade which was followed by two tasks. Task 1, was a 2-choice auditory discrimination task and Task 2 was a 2-choice visual localization task. We varied the interval between the onsets of the two targets associated with these two tasks (using TTOAs of 200, 400, or 800 msec). As expected the visual task suffered from a robust PRP effect (substantially delayed RTs at the shorter TTOAs). There was also a robust IOR effect with RTs to localize visual targets being slower when the targets were presented at a previously fixated location. Importantly, and in striking to our previous results wherein we generated the input form of IOR, in the present study there was an additive effect between IOR and TTOA on RT2. As implied by the locus of slack logic, we therefore conclude that the form of IOR generated when the oculomotor system is activated affects a late stage of processing. Converging evidence for this conclusion, from a variety of neuroscientific methods, is presented and the dearth of such evidence about the input form of IOR is noted.

Quasi-Randomized Trial of Contact With Nature and Effects on Attention in Children.

Children today spend less time in nature than previous generations and there is concern that this shift negatively impacts children's cognitive abilities, particularly their ability to direct their attention. Theories, such as the Attention Restoration Theory (ART), suggest that contact with nature may replenish endogenous attention (e.g., directed, voluntary attention). There is a lack of rigorous research on how contact with nature is associated with attentional performance in children. This study employed a quasi-experimental design and included a sample of typically developing children to investigate performance on computerized endogenous and exogenous attention tasks before and after exposure to one of two interventions - a 30-min walk in either an urban (n = 30) or natural (forested, n = 30) environment. The two experimental groups were equivalent with regard to sex ratio, age, IQ, and connectedness to nature. Attention was assessed using the Combined Attention Systems Test (CAST), a state-of-the-art assessment tool designed to evaluate exogenous and endogenous attention characteristics. Bayesian hierarchical modeling of both response time (RT) and error rate (ER) was employed to evaluate the fixed effect of attentional measures and interactions with session and group. Consistent with predictions of ART, results support credible effects of the nature intervention on two measures of endogenous attention: Alerting RT: d = 0.85 (95% CI: 0.21-1.8), Orienting ER: d = 1.45 (95% CI: 0.17-7.18), but not on any of the measures of exogenous attention. Clinical Trial Registration: https://www.isrctn.com/, identifier ISRCTN17762011.

How Does Spatial Attention Influence the Probability and Fidelity of Colour Perception?

Existing research has found that spatial attention alters how various stimulus properties are perceived (e.g., luminance, saturation), but few have explored whether it improves the accuracy of perception. To address this question, we performed two experiments using modified Posner cueing tasks, wherein participants made speeded detection responses to peripheral colour targets and then indicated their perceived colours on a colour wheel. In E1, cues were central and endogenous (i.e., prompted voluntary attention) and the interval between cues and targets (stimulus onset asynchrony, or SOA) was always 800 ms. In E2, cues were peripheral and exogenous (i.e., captured attention involuntarily) and the SOA varied between short (100 ms) and long (800 ms). A Bayesian mixed-model analysis was used to isolate the effects of attention on the probability and the fidelity of colour encoding. Both endogenous and short-SOA exogenous spatial cueing improved the probability of encoding the colour of targets. Improved fidelity of encoding was observed in the endogenous but not in the exogenous cueing paradigm. With exogenous cues, inhibition of return (IOR) was observed in both RT and probability at the long SOA. Overall, our findings reinforce the utility of continuous response variables in the research of attention.

Biomechanical Comparison of the Reverse Hyperextension Machine and the Hyperextension Exercise.

Lawrence, MA, Chin, A, and Swanson, BT. Biomechanical comparison of the reverse hyperextension machine and the hyperextension exercise. J Strength Cond Res 33(8): 2053-2056, 2019-The purpose of this study was to compare activation of the erector spinae, gluteus maximus, and biceps femoris muscles, lower back extension moment, and lower extremity range of motion (ROM) between the reverse hyperextension (RHE) and hyperextension (HE) exercises. Motion and muscle activation of the trunk and lower extremity were measured while 20 recreationally active individuals performed 2 sets of 10 repetitions of each exercise. Equivalent loads were used for each exercise. Peak, average, and integrated muscle activity, low back moment, and ROM between the trunk and pelvis and the thigh and trunk were calculated. A Wilcoxon signed-rank test (p = 0.05) revealed significantly greater integrated activity of the biceps femoris and gluteus maximus during the HE exercise. The RHE exercise generated greater peak (+129%), integrated (+63%), and mean (+78%) low back moment as compared to the HE exercise. The RHE resulted in a significantly greater thigh to trunk ROM, 76.6 compared with 64.7. However, the RHE used less lumbar flexion, 20.4 compared with 31.1 for the HE. The RHE movement profile is preferable because it provides greater hip ROM with less angular stress and equivalent erector spinae activity.

Agility and Vertical Jump Performances Are Impacted by Acute Cool Exposure.

Carlson, LA, Fowler, C, and Lawrence, MA. Agility and vertical jump performances are impacted by acute cool exposure. J Strength Cond Res 33(6): 1649-1653, 2019-Outdoor sports teams may be exposed to acute cold stress during competition, which may affect performance. Limited research has explored the effects of cold exposure on athletic components. The purpose of this study was to examine the effects of an acute whole-body cool exposure on pro-agility, vertical jump, and sprint performances. Eleven lightly clothed (∼0.3 clo) and not cold acclimatized volunteers (10/1 women/men: age 20.5 ± 0.5 years; height 1.65 ± 0.09 m; mass 63.3 ± 8.9 kg; body fat 21.3 ± 7.6%) completed performance tests in both thermoneutral (17.2° C, 36% relative humidity, Biddeford, ME, USA) and cool (6.1° C, 72% relative humidity, Thorsmörk, Iceland) ambient temperatures. Before completing the performance tests, subjects engaged in a 5-minute stretching routine and were subsequently exposed to either a thermoneutral or cool ambient environment for 15 minutes. Performance tests included 3 trials of maximal vertical jumps, and 2 trials of both the 36.6-m sprint and pro-agility tests. Mean performance and lactate values were compared via paired t-tests. Pro-agility completion time was significantly (p ≤ 0.05) slower in the cool (5.63 ± 0.33 seconds) than thermoneutral (5.43 ± 0.26 seconds) environment. Vertical jump was significantly (p ≤ 0.05) lower in the cool (0.36 ± 0.07 m) than thermoneutral (0.41 ± 0.10 m) environment. Sprint performance and lactate values were unaffected by the cool exposure. Brief cool exposure seems to influence agility and vertical jump performances. Our results suggest that it would be prudent for athletes and coaches to consider the ambient environment when preparing for competition.

Influence of Exercise Time of Day on Salivary Melatonin Responses.

BACKGROUND: Sleep deprivation negatively affects cognition, pain, mood, metabolism, and immunity, which can reduce athletic performance. Melatonin facilitates sleepiness and may be affected by the proximity of exercise to sleep. PURPOSE: To evaluate the influence of exercise time of day on salivary melatonin (s-melatonin) responses. METHODS: Twelve regularly exercising men (age 20.75 [0.62] y, height 1.75 [0.04] m, mass 73.63 [10.43] kg, and maximal oxygen consumption 57.72 [6.11] mL/kg/min) participated in a randomized, crossover design. Subjects completed 3 protocols-morning exercise (09:00 h), afternoon exercise (16:00 h), and no exercise (CON)-at least 5 d apart. Exercise sessions consisted of 30 min of steady-state running at 75% of maximal oxygen consumption. Saliva was collected via passive drool at 20:00, 22:00, and 03:00 h following all sessions. RESULTS: Repeated-measures analysis of variance revealed significant time (P = .001) and condition (P = .026) effects for melatonin. Levels of s-melatonin were significantly increased at 03:00 h compared with 20:00 and 22:00 h for all conditions. Post hoc analyses revealed that s-melatonin at 22:00 h was significantly higher after morning exercise (16.5 [7.5] pg/mL) compared with afternoon exercise (13.7 [6.1] pg/mL) sessions (P = .03), whereas neither exercise condition significantly differed from the control (P > .05). CONCLUSIONS: It appears that exercising in the afternoon may blunt melatonin secretion compared with morning exercise. If sleep is an issue, morning exercise may be preferable to afternoon exercise.

Effects of the Safety Squat Bar on Trunk and Lower-Body Mechanics During a Back Squat.

Hecker, KA, Carlson, LA, and Lawrence, MA. Effects of the safety squat bar on trunk and lower-body mechanics during a back squat. J Strength Cond Res 33(7S): S45-S51, 2019-The purpose of this study was to determine whether the safety squat bar (SSB) alters the mechanics and muscle activity of a back squat compared with a standard barbell (ST). Motion and muscle activation of the trunk and lower extremity were measured while 12 competitive powerlifters (8 males, 4 females, age 31.5 ± 6.3 years, body mass 88.1 ± 20.7 kg, competitive lifting experience 3.3 ± 2.8 years) squatted 3 sets of 5 repetitions at 75% of their 3 repetition maximum (3RM). Mean muscle activity and peak joint flexion angles were measured for the trunk and one lower extremity. A repeated-measures analysis of variance (p = 0.05) revealed an 11.3% decrease in 3RM when using the SSB. When using the SSB, there was a decrease in trunk and hip flexion (7.3 and 5.7° respectively) and a 50.3% increase in lower trapezius activation. However, using the SSB decreased activation of the rectus abdominis (46.3%), medial hamstring (17.1%), lateral hamstring (15.1%), vastus lateralis (9.3%), and medial gastrocnemius (18.8%). Squatting with the SSB resulted in a more upright trunk angle, which places less stress on the lower back, a commonly injured area when squatting. Decreases in lower-extremity muscle activation are likely due to the decreased load used, suggesting that the SSB may not be as effective as a standard bar to increase lower-extremity strength. However, the increase in the lower trapezius with the lighter load suggests that midback musculature may be challenged more by the SSB than a standard barbell.

Using Rescorla's truly random control condition to measure truly exogenous covert orienting.

Studies of exogenous covert orienting use peripheral cues (stimuli) that are spatially uninformative about the locations of subsequent targets. When the time course of the cue's influence on performance is explored (by varying the cue target onset asynchrony; CTOA), a biphasic pattern is usually seen with better performance at the cued location when the CTOA is short (typically attributed to attentional capture) and worse performance at the cued location when the CTOA is long (attributed to inhibition of return). However, while spatially uninformative, these cues (even when a nonaging foreperiod is used) entail a temporal contingency with the subsequent target. Consequently, this so-called capture may reflect an unintended consequence of endogenous allocation of temporal attention. Following Lawrence and Klein (Journal of Experimental Psychology: General, 142(2), 560-572, 2013) we used Rescorla's (Psychological Review, 74, 71-80, 1967) truly random control condition to ensure that the spatially uninformative peripheral stimuli were temporally completely uninformative. Even such completely uninformative peripheral stimuli generated the prototypical biphasic pattern.

Hydration Status and Thermoregulatory Responses in Drivers During Competitive Racing.

Carlson, LA, Lawrence, MA, and Kenefick, RW. Hydration status and thermoregulatory responses in drivers during competitive racing. J Strength Cond Res 32(7): 2061-2065, 2018-Stock car drivers are exposed to high ambient temperatures, further complicated by the fact that they are encapsulated in protective clothing; however, the hydration status of these drivers has not been determined. This study quantified the degree of fluid losses during a competitive event in hot conditions. Nine male stock car drivers (29.6 ± 9.4 years, 177.8 ± 3.0 cm, 81.5 ± 18.5 kg) were studied during a Pro Series Division NASCAR race. Sweat rate (SR) and dehydration was determined through nude body weights (BWs). Prerace BW was 81.5 ± 18.5 kg and decreased to 81.1 ± 18.5 kg after race (p = 0.001). Body weight loss after race was 0.77 ± 0.3% and mean SR was 0.63 ± 0.4 L·h. Intestinal core temperature increased from 38.0 ± 0.4 to 38.5 ± 0.4° C after race (p = 0.001). Skin temperature increased from 35.8 ± 0.8 to 36.9 ± 0.8° C after race (p = 0.001), whereas the core-to-skin temperature gradient narrowed from 2.2 ± 0.9 to 1.6 ± 0.9° C, before race to after race (p = 0.001). Heart rates after race were 89 ± 0.0% of the drivers' age-predicted maximum heart rate (HR). Fluid losses during competitive racing can be significant. Without a fluid replacement strategy, fluid losses may exceed 3% of BW and could negatively impact driving performance in longer races.

Effect of an Unstable Load on Primary and Stabilizing Muscles During the Bench Press.

Ostrowski, SJ, Carlson, LA, and Lawrence, MA. Effect of an unstable load on primary and stabilizing muscles during the bench press. J Strength Cond Res 31(2): 430-434, 2017-Unstable resistance exercises are performed to increase activity of stabilizing muscles. The premise is that this increase in activity will yield greater strength gains than traditional resistance exercises. The purpose of this study was to determine if an unstable load increases muscle activity of stabilizing muscles during a bench press as compared with a standard bench press with a typical load. Fifteen resistance-trained males (age 24.2 ± 2.7 years, mass 84.8 ± 12.0 kg, height 1.77 ± 0.05 m, weight lifting experience 9.9 ± 3.4 years, and bench press 1 repetition maximum [1RM] 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (75% 1RM) and unstable (60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). Muscle activity was compared using a multivariate analysis of variance to determine significant (p ≤ 0.05) phase and condition differences. The right and left biceps and the left middle deltoid were significantly more active in the unstable condition. Some of the stabilizing muscles were found to be significantly more active in the unstable condition with 15% less weight. Therefore, bench pressing with an unstable load appears promising in activating stabilizing musculature compared with pressing a typical barbell.

Nonlinear Analysis of an Unstable Bench Press Bar Path and Muscle Activation.

Lawrence, MA, Leib, DJ, Ostrowski, SJ, and Carlson, LA. Nonlinear analysis of an unstable bench press bar path and muscle activation. J Strength Cond Res 31(5): 1206-1211, 2017-Unstable resistance exercises are typically performed to improve the ability of stabilizing muscles to maintain joint integrity under a load. The purpose of this study was to examine the effects of an unstable load (as provided by a flexible barbell and a load suspended by elastic bands) on the bar path, the primary musculature, and stabilizing musculature while bench pressing using nonlinear analyses. Fifteen resistance-trained men (age 24.2 ± 2.7 years, mass 84.1 ± 12.0 kg, height 1.77 ± 0.05 m, 9.9 ± 3.4 years of lifting experience, and bench press 1 repetition maximum (RM) 107.5 ± 25.9 kg) volunteered for this study. Subjects pressed 2 sets of 5 repetitions in both stable (total load 75% 1RM) and unstable (total load 60% 1RM) conditions using a standard barbell and a flexible Earthquake bar, respectively. Surface electromyography was used to detect muscle activity of primary movers (pectoralis major, anterior deltoid, and triceps) and bar stabilizing musculature (latissimus dorsi, middle and posterior deltoid, biceps brachii, and upper trapezius). During the unstable condition, the bar moved in more ways and was less predictable in the mediolateral and anteroposterior directions. However, the muscle activation patterns of all muscles were more constrained with the unstable barbell. These findings suggest that the unstable condition was more challenging to control, but subjects controlled the instability by contracting their muscles in a more stable pattern or "staying tight" throughout the exercise.

Salivary Lymphocyte Responses Following Acute Anaerobic Exercise in a Cool Environment.

Carlson, LA, Lawrence, MA, LeCavalier, K, and Koch, AJ. Salivary lymphocyte responses following acute anaerobic exercise in a cool environment. J Strength Cond Res 31(5): 1236-1240, 2017-The purpose of this study was to examine the impact of anaerobic training on salivary lymphocytes (s-LYMPH), and further determine whether these responses differ between cool vs. thermoneutral environments. Nine lightly clothed (∼0.3 clo) volunteers (7/2 women/men: age, 21 ± 1 years; height, 168.7 ± 7.3 cm; weight, 66.4 ± 8.4 kg; body fat, 20.6 ± 7.6%) completed speed, agility, and quickness (SAQ) sessions in both warm (18.9° C; Biddeford) and cool (10.4° C; Thorsmörk) temperatures. The SAQ sessions consisted of 3 trials of 20-m sprints, 40-m sprints, t-tests, and box drills, and two 300-yd shuttle runs in both conditions. Saliva samples via passive drool were collected at baseline, immediately postexercise, and after 2 hours of recovery. The s-LYMPH increased (p < 0.001) immediately postexercise, followed by a decrease (p < 0.001) below baseline values after 2 hours of recovery in both environments. The s-LYMPH counts were lower (p < 0.001) for the cool environment than for the thermoneutral environment. The s-LYMPH counts increased postexercise, followed by a decrease after 2 hours of recovery regardless of environment. Acute anaerobic exercise induced transient changes in s-LYMPH counts similar to that observed in peripheral blood. Compared with baseline measures, changes in s-LYMPH were of a smaller magnitude after exercise in the cool environment compared with thermoneutral environment. In summary, there is no indication that exercise in the cool environment presented a greater challenge to the subjects' immunity. Rather, these data indicate exercise in a cool environment produces smaller fluctuations in salivary immune cells compared with resting levels.