Effects of pre-exhausting the biceps brachii muscle on the performance of the front lat pull-down exercise using different handgrip positions

Pre-exhaustion Training, a Narrative Review of the Acute Responses and Chronic Adaptations

Pre-exhaustion (PE) is a popular resistance training strategy that involves performing a single-joint exercise followed by a multi-joint exercise with minimal recovery between the transition. This approach is widely used by bodybuilding athletes and resistance training (RT) enthusiasts with the aim of enhancing muscle strength and hypertrophy. The present paper aimed to provide a narrative review as to the effects of the PE method on different acute and chronic outcomes, and discuss relevant practical applications. When considering the body of literature as a whole, we conclude that current evidence does not support a benefit to the PE method compared to traditional RT models regarding chronic improvements in strength, hypertrophy and body composition. However, the heterogeneous study designs confound the ability to draw strong conclusions on the topic. Further investigations are warranted with strict control of study variables to better elucidate what, if any, benefits may be obtained by the PE method.

Muscle activation and biceps brachii strength under manual fixation of the scapula and different loading conditions

BACKGROUND: Few studies have reported the contribution of isometric-specific exercise of the biceps brachii muscle to increased strength under manual fixation of the scapula. OBJECTIVE: To investigate the activation amplitude of the biceps brachii (BB), serratus anterior (SA), and upper trapezius (UT) in a supine lying posture based on various exercise conditions. METHODS: The EMG activity of BB, SA, and UT was measured in 25 healthy adults while performing maximal elbow flexion exercise with or without manual stabilization of the scapula in two different loading conditions. RESULTS: Muscle activation of the BB was significantly greater when performed with manual fixation of the scapula under the wrist-loading exercise condition (p< 0.05) but manual fixation of the scapula or absence thereof did not have an effect. Elbow flexion force was significantly increased when applying manual fixation to the scapula in both the hand and wrist-loading exercise conditions (p< 0.05). There were no interaction effects between exercise conditions and manual fixation (with or without) in any of the EMG activation values (p> 0.05). CONCLUSION: Manual stabilization of the scapula is a useful therapeutic technique to increase BB strength. Such an intervention may also be indicated for accurate strength measurement of this muscle.

Pre-exhaustion Exercise Differentially Influences Neuromuscular Fatigue Based on Habitual Physical Activity History

ABSTRACT

Harlan, KG, Merucci, RB, Weaver, JJ, Windle, TC, and Malek, MH. Pre-exhaustion exercise differentially influences neuromuscular fatigue based on habitual physical activity history. J Strength Cond Res 35(3): 739-745, 2021-Although there is anecdotal evidence of a potential physiological benefit of pre-exhaustion exercise to enhance muscular recruitment, few studies have systematically examined the effect on neuromuscular activity. Moreover, a subject's habitual physical activity history may, in part, contribute to the muscle's response on a subsequent workbout after a single pre-exhaustion workbout. To date, no studies have examined the effect of pre-exhaustion exercise on the electromyographic fatigue threshold (EMGFT). The purpose of this study, therefore, is to determine whether pre-exhaustion exercise influences the EMGFT. Specifically, we were interested in determining whether or not there is a dichotomous response to pre-exhaustion exercise based on the individual's habitual physical activity history. Thus, we hypothesized that healthy active subjects would have reduced EMGFT values, whereas elite runners would have increased EMGFT values as a result of the pre-exhaustion exercise. Eight healthy college-aged men (mean ± SEM, age = 24.5 ± 0.3 years; body mass = 83.1 ± 3.0 kg; and height = 1.80 ± 0.02 m) and 9 elite runners (mean ± SEM, age = 23.4 ± 0.7 years; body mass = 70.3 ± 2.7 kg; and height = 1.79 ± 0.03 m) participated in current study. Each subject visited the laboratory on 2 occasions separated by 7 days and performed the single-leg knee-extensor ergometry test. For one of the visits, the subjects performed the Thorstensson test (50 continuous, concentric knee extensions) before the single-leg knee-extensor ergometry. The EMGFT was measured on both visits for all subjects. For healthy subjects, we found that the EMGFT was significantly reduced after performing the 50 isokinetic knee extensions (control: 27 ± 6 W vs. Thorstensson: 21 ± 6.0 W; p = 0.001), whereas for elite runners, there was no significant mean differences between the 2 visits (control: 38 ± 3 W vs. Thorstensson: 39 ± 2 W; p = 0.813). These results suggest that 50 repetition of isokinetic muscle action, as a method of pre-exhausting the quadriceps femoris muscles, may be influenced by the subject's habitual exercise history.

Different Shoulder Exercises Affect the Activation of Deltoid Portions in Resistance-Trained Individuals

The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni’s posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.