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.

Increased Rate of Heat Storage, and No Performance Benefits, With Caffeine Ingestion Before a 10-km Run in Hot, Humid Conditions.

PURPOSE: Although the effect of caffeine in thermoneutral or cool environmental conditions has generally shown performance benefits, its efficacy in hot, humid conditions is not as well known. The purpose of this study was to further examine the effect of caffeine ingestion on endurance running performance in the heat. METHODS: Ten trained endurance runners (6 males; mean [SD] age = 26 [9] y, height = 176.7 [5.1] cm, and mass = 72.1 [8.7] kg) came to the lab for 4 visits. The first was a VO2max test to determine cardiorespiratory fitness; the final 3 visits were 10-km runs in an environmental chamber at 30.6°C and 50% relative humidity under different conditions: 3 mg·kg-1 body mass (low caffeine dosage), 6 mg·kg-1 (moderate caffeine dosage), and a placebo. Repeated-measures analyses of variance were used to determine the effect of condition on the 10-km time, heart rate, core temperature, rating of perceived exertion, and thermal sensation. RESULTS: There was no difference in the 10-km time between the placebo (53.2 [8.0] min), 3-mg·kg-1 (53.4 [8.4]), and 6-mg·kg-1 (52.7 [8.2]) conditions (P = .575, ηp2=.060 ). There was not a main effect of average heart rate (P = .406, ηp2=.107 ), rating of perceived exertion (P = .151, ηp2=.189 ), or thermal sensation (P = .286, ηp2=.130 ). There was a significant interaction for core temperature (P = .025, ηp2=.170 ); the moderate-dosage caffeine condition showed a higher rate of rise in core temperature (0.26 [0.08] °C·km-1 vs 0.20 [0.06] and 0.19 [0.10] °C·km-1 in the low-caffeine and placebo conditions, respectively). CONCLUSION: The results support previous research showing a thermogenic effect of caffeine, as the moderate-dosage condition led to a greater rate of heat storage and no performance benefits.

A Couple-Based Psychological Treatment for Chronic Pain and Relationship Distress.

Chronic pain impacts individuals with pain as well as their loved ones. Yet, there has been little attention to the social context in individual psychological treatment approaches to chronic pain management. With this need in mind, we developed a couple-based treatment, "Mindful Living and Relating," aimed at alleviating pain and suffering by promoting couples' psychological and relational flexibility skills. Currently, there is no integrative treatment that fully harnesses the power of the couple, treating both the individual with chronic pain and the spouse as two individuals who are each in need of developing greater psychological and relational flexibility to improve their own and their partners' health. Mindfulness, acceptance, and values-based action exercises were used to promote psychological flexibility. The intervention also targets relational flexibility, which we define as the ability to interact with one's partner, fully attending to the present moment, and responding empathically in a way that serves one's own and one's partner's values. To this end, the intervention also included exercises aimed at applying psychological flexibility skills to social interactions as well as emotional disclosure and empathic responding exercises to enhance relational flexibility. The case presented demonstrates that healthy coping with pain and stress may be most successful and sustainable when one is involved in a supportive relationship with someone who also practices psychological flexibility skills and when both partners use relational flexibility skills during their interactions.