Partial Range of Motion Exercise Is Effective for Facilitating Muscle Hypertrophy and Function Through Sustained Intramuscular Hypoxia in Young Trained Men

Optimizing Resistance Training Technique to Maximize Muscle Hypertrophy: A Narrative Review

Regimented resistance training (RT) has been shown to promote increases in muscle size. When engaging in RT, practitioners often emphasize the importance of appropriate exercise technique, especially when trying to maximize training adaptations (e.g., hypertrophy). This narrative review aims to synthesize existing evidence on what constitutes proper RT exercise technique for maximizing muscle hypertrophy, focusing on variables such as exercise-specific kinematics, contraction type, repetition tempo, and range of motion (ROM). We recommend that when trying to maximize hypertrophy, one should employ a ROM that emphasizes training at long muscle lengths while also employing a repetition tempo between 2 and 8 s. More research is needed to determine whether manipulating the duration of either the eccentric or concentric phase further enhances hypertrophy. Guidelines for body positioning and movement patterns are generally based on implied theory from applied anatomy and biomechanics. However, existing research on the impact of manipulating these aspects of exercise technique and their effect on hypertrophy is limited; it is therefore suggested that universal exercise-specific kinematic guidelines are followed and adopted in accordance with the above recommendations. Future research should investigate the impact of stricter versus more lenient exercise technique variations on hypertrophy.

Greater Gastrocnemius Muscle Hypertrophy After Partial Range of Motion Training Performed at Long Muscle Lengths

ABSTRACT

Kassiano, W, Costa, B, Kunevaliki, G, Soares, D, Zacarias, G, Manske, I, Takaki, Y, Ruggiero, MF, Stavinski, N, Francsuel, J, Tricoli, I, Carneiro, MAS, and Cyrino, ES. Greater gastrocnemius muscle hypertrophy after partial range of motion training performed at long muscle lengths. J Strength Cond Res 37(9): 1746-1753, 2023-Whether there is an optimal range of motion (ROM) to induce muscle hypertrophy remains elusive, especially for gastrocnemius. This study aimed to compare the changes in gastrocnemius muscle thickness between calf raise exercise performed with full ROM (FULL ROM ), partial ROM performed in the initial (INITIAL ROM ), and final (FINAL ROM ) portions of the ROM. Forty-two young women performed a calf training program for 8 weeks, 3 days·week -1 , with differences in the calf raise ROM configuration. The calf raise exercise was performed in a pin-loaded, horizontal, leg-press machine, in 3 sets of 15-20 repetition maximum. The subjects were randomly assigned to 1 of the 3 groups: FULL ROM (ankle: -25° to +25°), INITIAL ROM (ankle: -25° to 0°), and FINAL ROM (ankle: 0° to +25°), where 0° was defined as an angle of 90° of the foot with the tibia. The muscle thickness measurements of medial and lateral gastrocnemius were taken by means of B-mode ultrasound. INITIAL ROM elicited greater medial gastrocnemius increases than FULL ROM and FINAL ROM (INITIAL ROM = +15.2% vs. FULL ROM = +6.7% and FINAL ROM = +3.4%; p ≤ 0.009). Furthermore, INITIAL ROM elicited greater lateral gastrocnemius increases than FINAL ROM (INITIAL ROM = +14.9% vs. FINAL ROM = +6.2%; p < 0.024) but did not significantly differ from FULL ROM (FULL ROM = +7.3%; p = 0.060). The current results suggest that calf training performed at longer muscle lengths may optimize gastrocnemius muscle hypertrophy in young women. Therefore, when prescribing hypertrophy-oriented training, the inclusion of the calf raise exercise performed with partial ROM in the initial portion of the excursion should be considered.

Effects of Drop Sets on Skeletal Muscle Hypertrophy: A Systematic Review and Meta-analysis

BACKGROUND

One of the most popular time-efficient training methods when training for muscle hypertrophy is drop sets, which is performed by taking sets to concentric muscle failure at a given load, then making a drop by reducing the load and immediately taking the next set to concentric or voluntary muscle failure. The purpose of this systematic review and meta-analysis was to compare the effects of drop sets over traditional sets on skeletal muscle hypertrophy.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The SPORTDiscus and MEDLINE/PubMed databases were searched on April 9, 2022, for all studies investigating the effects of the drop set training method on muscle hypertrophy that meets the predefined inclusion criteria. Comprehensive Meta-Analysis Version 3 (Biostat Inc., Englewood Cliffs, NJ, USA) was used to run the statistical analysis. Publication bias was assessed through visual inspection of the funnel plots for asymmetry and statistically by Egger's regression test with an alpha level of 0.10.

RESULTS

Six studies met the predefined inclusion criteria. The number of participants in the studies was 142 (28 women and 114 men) with an age range of 19.2-27 years. The average sample size was 23.6 ± 10.9 (range 9-41). Five studies were included in the quantitative synthesis. Meta-analysis showed that both the drop set and traditional training groups increased significantly from pre- to post-test regarding muscle hypertrophy (drop set standardized mean difference: 0.555, 95% CI 0.357-0.921, p < 0.0001; traditional set standardized mean difference: 0.437, 95% CI 0.266-0.608, p < 0.0001). No significant between-group difference was found (standardized mean difference: 0.155, 95% CI - 0.199 to - 0.509, p = 0.392).

CONCLUSIONS

The results of this systematic review and meta-analysis indicate that drop sets present an efficient strategy for maximizing hypertrophy in those with limited time for training. There was no significant difference in hypertrophy measurements between the drop set and traditional training groups, but some of the drop set modalities took half to one-third of the time compared with traditional training.

Which ROMs Lead to Rome? A Systematic Review of the Effects of Range of Motion on Muscle Hypertrophy

ABSTRACT

Kassiano, W, Costa, B, Nunes, JP, Ribeiro, AS, Schoenfeld, BJ, and Cyrino, ES. Which ROMs lead to Rome? a systematic review of the effects of range of motion on muscle hypertrophy. J Strength Cond Res XX(X): 000-000, 2022-Resistance exercise range of motion (ROM) influences muscular adaptations. However, there are no consistent practical guidelines about the optimal ROM for maximizing muscle hypertrophy. The objective of this article was to systematically review the literature for studies that compared the effects of full ROM (fROM) and partial ROM (pROM) on muscle hypertrophy. PubMed/MEDLINE, Scopus, and Web of Science databases were searched to identify articles from the earliest record up to and including April 2022. We calculated the effect size (ES) scores of the variables of interest. Eleven studies were included in the review. Full ROM and pROM performed in the initial part of the ROM elicited greater muscle hypertrophy of the rectus femoris, vastus lateralis, biceps brachii, and brachialis distal sites (between-groups ES: 0.20-0.90) than pROM performed in the final part of the ROM. fROM elicited greater muscle growth on the gluteus maximus and adductors than pROM in the final part of the ROM (between-groups ES: 0.24-0.25). Initial pROM produced more favorable proximal rectus femoris hypertrophy than fROM (between-groups ES: 0.35-0.38). pROM in the middle part of the ROM elicited greater triceps brachii hypertrophy than fROM (between-group ES: 1.21). In conclusion, evidence suggests that when training at a longer muscle length-through either pROM or fROM-some muscles, such as quadriceps femoris, biceps brachii, and triceps brachii, tend to experience optimal growth. Thus, the use pROM in the initial part of the excursion in combination with fROM training should be considered when prescribing hypertrophy-oriented resistance training programs.

The effect of repetition tempo on cardiovascular and metabolic stress when time under tension is matched during lower body exercise

PURPOSE

To investigate the effect of repetition tempo on cardiovascular and metabolic stress when time under tension (TUT) and effort are matched during sessions of lower body resistance training (RT).

METHODS

In a repeated-measures, cross-over design, 11 recreationally trained females (n = 5) and males (n = 6) performed 5 sets of belt squats under the following conditions: slow-repetition tempo (SLOW; 10 reps with 4-s eccentric and 2-s concentric) and traditional-repetition tempo (TRAD; 20 reps with 2-s eccentric and 1-s concentric). TUT (60 s) was matched between conditions and external load was adjusted so that lifters were close to concentric muscular failure at the end of each set. External load, total volume load (TVL), impulse (IMP), blood lactate, ratings of perceived exertion (RPE), HR, and muscle oxygenation were measured.

RESULTS

Data indicated that TVL (p < 0.001), blood lactate (p = 0.017), RPE (p = 0.015), and HR (p < 0.001) were significantly greater during TRAD while external load (p = 0.030) and IMP (p = 0.002) were significantly greater during SLOW. Whether it was expressed as minimal values or change scores, muscle oxygenation was not different between protocols.

CONCLUSION

When TUT is matched, TVL, cardiovascular stress, metabolic stress, and perceived exertion are greater when faster repetition tempos are used. In contrast, IMP and external load are greater when slower repetition tempos are used.

The use of a cold pack during resistance exercises is effective for reducing intramuscular oxygenation and increasing myoelectric activity

[Purpose] The purpose of this study was to determine the efficacy of using a cold pack while doing resistance exercises for enhancing muscle strength and muscle hypertrophy through decreased intramuscular oxygenation and/or increased myoelectric activity. [Participants and Methods] Twenty-four resistance-trained males (age: 26.4 ± 8.4 years, height: 169.3 ± 5.2 cm, body weight: 74.7 ± 8.8 kg) involved in this study. All the participants completed two experimental sessions in random order (cold pack resistance exercise and resistance exercise) with a 3-day interval. Four types of resistance exercises (4 sets × 8 repetitions with an 8-repetition maximum) targeting the right triceps brachii muscle were performed in both the experimental sessions. [Results] The percentage baseline oxyhemoglobin/myoglobin level during resistance exercise was significantly lower, the half-recovery time of muscle oxygenation in intervals between sets was significantly longer, and the myoelectric activity was significantly higher in the cold pack resistance exercise than in the resistance exercise session. [Conclusion] The results suggest that using a cold pack with resistance exercises is effective in inducing intramuscular deoxygenation and increasing myoelectric activity and may be useful for increasing muscle strength and inducing hypertrophy.

May the Force and Mass Be With You-Evidence-Based Contribution of Mechano-Biological Descriptors of Resistance Exercise

Skeletal muscle is one of the most important tissues of the human body. It comprises up to 40% of the body mass and is crucial to survival. Hence, the maintenance of skeletal muscle mass and strength is pivotal. It is well-established that resistance exercise provides a potent anabolic stimulus to increase muscle mass and strength in men and women of all ages. Resistance exercise consists of mechano-biological descriptors, such as load, muscle action, number of repetitions, repetition duration, number of sets, rest interval between sets, frequency, volitional muscular failure, and range of motion, which can be manipulated. Herein, we discuss the evidence-based contribution of these mechano-biological descriptors to muscle mass and strength.

Elbow Joint Angles in Elbow Flexor Unilateral Resistance Exercise Training Determine Its Effects on Muscle Strength and Thickness of Trained and Non-trained Arms

The present study compared two unilateral arm curl resistance exercise protocols with a different starting and finishing elbow joint angle in the same ROM for changes in elbow flexors strength and muscle thickness of the trained and non-trained arms. Thirty-two non-resistance trained young adults were randomly assigned to one of the three groups: extended joint training (0°–50°; EXT, n = 12); flexed joint training (80°–130°; FLE, n = 12); and non-training control (n = 8). The exercise training was performed by the dominant arms twice a week for 5 weeks with gradual increases in the training volume over 10 training sessions, and the non-dominant (non-trained) arms were investigated for the cross-education effect. Maximal voluntary contraction torque of isometric (MVC-ISO), concentric (MVC-CON), and eccentric contractions (MVC-ECC), and thickness (MT) of biceps brachii and brachialis of the trained and non-trained arms were assessed at baseline and 4–8 days after the last training session. The control group did not show significant changes in any variables. Significant (P < 0.05) increases in MVC-ISO torque (16.2 ± 12.6%), MVC-CON torque (21.1 ± 24.4%), and MVC-ECC torque (19.6 ± 17.5%) of the trained arm were observed for the EXT group only. The magnitude of the increase in MT of the trained arm was greater (P < 0.05) for EXT (8.9 ± 3.9%) than FLE (3.4 ± 2.7%). The cross-education effect was evident for MVC-ISO (15.9 ± 14.8%) and MVC-CON (16.7 ± 20.0%) torque of the EXT group only. These results suggest that resistance training at the extended elbow joint induces greater muscle adaptations and cross-education effects than that at flexed elbow joint.

Range of motion of resistance exercise affects the number of performed repetitions but not a time under tension

The resistance training volume along with the exercise range of motion has a significant impact on the training outcomes. Therefore, this study aimed to examine differences in training volume assessed by a number of performed repetitions, time under tension, and load-displacement as well as peak barbell velocity between the cambered and standard barbell bench press training session. The participants performed 3 sets to muscular failure of bench press exercise with the cambered or standard barbell at 50% of one-repetition maximum (1RM). Eighteen healthy men volunteered for the study (age = 25 ± 2 years; body mass = 92.1 ± 9.9 kg; experience in resistance training 7.3 ± 2.1 years; standard and cambered barbell bench press 1RM > 120% body mass). The t-test indicated a significantly higher mean range of motion for the cambered barbell in comparison to the standard (p < 0.0001; ES =  -2.24). Moreover, there was a significantly greater number of performed repetitions during the standard barbell bench press than cambered barbell (p < 0.0001) in a whole training session, while no difference was found in total time under tension (p = 0.22) and total load-displacement (p = 0.913). The two-way repeated-measures ANOVA indicated a significant barbell × set interaction effect for peak velocity (p = 0.01) and a number of repetitions (p = 0.015). The post-hoc analysis showed a significantly higher number of repetitions for standard than cambered barbell bench press in set 1 (p < 0.0001), set 3 (p < 0.0001) but not in set 2 (p = 0.066). Moreover, there was a significantly higher peak velocity during the cambered than standard barbell bench press in set 1 (p < 0.0001), and set 2 (p = 0.049), but not in set 3 (p = 0.063). No significant differences between corresponding sets of the standard and cambered barbell bench press in time under tension and load-displacement were found. However, concentric time under tension was significantly higher during cambered barbell bench press in all sets (p < 0.05) when compared to the standard barbell bench press, while eccentric time under tension was significantly lower during the cambered than standard barbell bench presses only in the set 3 (p = 0.001). In summary, this study briefly showed that measuring training volume by the number of performed repetitions is not reliable when different exercise range of motion is used.

Effects of range of motion on resistance training adaptations: A systematic review and meta-analysis

BACKGROUND

Nowadays, there is a lack of consensus and high controversy about the most effective range of motion (ROM) to minimize the risk of injury and maximize the resistance training adaptations.

OBJECTIVE

To conduct a systematic review and meta-analysis of the scientific evidence examining the effects of full and partial ROM resistance training interventions on neuromuscular, functional, and structural adaptations.

METHODS

The original protocol (CRD42020160976) was prospectively registered in the PROSPERO database. Medline, Scopus, and Web of Science databases were searched to identify relevant articles from the earliest record up to and including March 2021. The RoB 2 and GRADE tools were used to judge the level of bias and quality of evidence. Meta-analyses were performed using robust variance estimation with small-sample corrections.

RESULTS

Sixteen studies were finally included in the systematic review and meta-analyses. Full ROM training produced significantly greater adaptations than partial ROM on muscle strength (ES = 0.56, p = 0.004) and lower-limb hypertrophy (ES = 0.88, p = 0.027). Furthermore, although not statistically significant, changes in functional performance were maximized by the full ROM training (ES = 0.44, p = 0.186). Finally, no significant superiority of either ROM was found to produce changes in muscle thickness, pennation angle, and fascicle length (ES = 0.28, p = 0.226).

CONCLUSION

Full ROM resistance training is more effective than partial ROM to maximize muscle strength and lower-limb muscle hypertrophy. Likewise, functional performance appears to be favored by the use of full ROM exercises. On the contrary, there are no large differences between the full and partial ROM interventions to generate changes in muscle architecture.

Placing Greater Torque at Shorter or Longer Muscle Lengths? Effects of Cable vs. Barbell Preacher Curl Training on Muscular Strength and Hypertrophy in Young Adults

Muscular strength and hypertrophy following resistance training may be obtained in different degrees depending on the approach performed. This study was designed to compare the responses of the biceps brachii to two preacher curl exercises, one performed on a cable-pulley system (CAB; in which a greater torque was applied during the exercise when elbows were flexed and biceps shortened) and one performed with a barbell (BAR; in which greater torque was applied when the elbows were extended and biceps stretched). Thirty-five young adults (CAB: 13 men, 5 women; BAR: 12 men, 5 women; age = 24 ± 5 years) performed a resistance training program three times per week for 10 weeks, with preacher curl exercises performed in three sets of 8–12 repetitions. Outcomes measured included elbow flexion peak isokinetic torque at angles of 20°, 60°, and 100° (considering 0° as elbow extended), and biceps brachii thickness (B-mode ultrasound). Following the training period, there were significant increases for both groups in elbow flexion peak torque at the 20° (CAB: 30%; BAR = 39%; p = 0.046), 60° (CAB: 27%; BAR = 32%; p = 0.874), and 100° (CAB: 17%; BAR = 19%; p = 0.728), and biceps brachii thickness (CAB: 7%; BAR = 8%; p = 0.346). In conclusion, gains in muscular strength were greater for BAR only at longer muscle length, whereas hypertrophy was similar regardless of whether torque emphasis was carried out in the final (CAB) or initial (BAR) degrees of the range of motion of the preacher curl in young adults.

Pre-stretching of the Hamstrings Before Squatting Acutely Increases Biceps Femoris Thickness Without Impairing Exercise Performance

Background: Bilateral squat exercise is widely used in resistance training (RT) programs to increase lower limb strength and muscle mass, but this exercise does not result in significant hypertrophy of the hamstrings. It has been speculated that stretching between sets with a certain degree of tension results in muscle hypertrophy, while acute stretching could decrease performance during maximal contractions.

Objective: This study investigated the acute effects of hamstring stretching before bilateral squatting on muscle thickness (MT), electromyography (EMG), and total training volume (TTV) on exercise performance.

Methods: Fourteen resistance-trained young men, with ∼7.5 years of RT experience, performed the 10 repetition maximum (RM) for the barbell squat in two sessions (test–retest) separated by period after 48 h. Participants engaged in two resistance exercise conditions separated by a 1 week recovery interval: one session employed hamstrings stretching and the other did not include hamstrings stretching. Before and after each resistance exercise session, the thickness of the quadriceps muscles and biceps femoris long head were obtained by ultrasound imaging. Moreover, the EMG amplitudes for the quadriceps muscles, biceps femoris, and iliocostalis muscles were recorded during back squat performance. The TTV was also evaluated for each exercise session.

Results: A significant increase in MT was observed after every set in both conditions for the evaluated quadriceps muscles (all p < 0.05), while for the biceps femoris, this effect was found only in the stretching condition (p < 0.05). EMG activity increased in the rectus femoris, vastus lateralis, and vastus medialis for the stretching condition. For the non-stretching condition, activity only increased in the vastus lateralis and medialis. There was no difference in EMG activity for the biceps femoris and iliocostalis in both conditions.

Conclusion: Stretching the hamstrings immediately before each set of the back squat can be used to acutely increase biceps femoris thickness without impairing squat performance.

Effects of range of motion on muscle development during resistance training interventions: A systematic review

The purpose of this study was to systematically review the literature as to the effects of performing exercise with a full versus partial range of motion (ROM) during dynamic, longitudinal resistance training (RT) programs on changes in muscle hypertrophy. Based on the available literature, we aimed to draw evidence-based recommendations for RT prescription. Six studies were identified as meeting inclusion criteria: four of these studies involved RT for the lower limbs while the other two focused on the upper extremities. The total combined sample of the studies was n = 135, which comprised 127 men and 8 women. The methodological quality of all included studies was deemed to be "excellent" based on the modified PEDro scale. When assessing the current body of literature, it can be inferred that performing RT through a full ROM confers beneficial effects on hypertrophy of the lower body musculature versus training with a partial ROM. Alternatively, research on the effects of ROM for the upper limbs is limited and conflicting, precluding the ability to draw strong practical inferences. No study to date has investigated how ROM influences muscle growth of the trunk musculature. Finally, some evidence indicates that the response to variations in ROM may be muscle-specific; however, this hypothesis also warrants further study.

Effects of Pre-exhaustion Versus Traditional Resistance Training on Training Volume, Maximal Strength, and Quadriceps Hypertrophy

BACKGROUND

The pre-exhaustion (PreEx) method is used as a resistance training (RT) method to increase muscle mass, yet the chronic effects of this method are poorly understood.

OBJECTIVE

Although readily prescribed as a RT method for promotion of muscle hypertrophy, few researches give light to gains made after chronic PreEx RT. Therefore, we compared the effects of traditional versus PreEx RT programs on muscle strength, body composition, and muscular hypertrophy in adult males.

METHODS

Untrained subjects (age: 31.37 ± 6.83 years; height: 175.29 ± 5.52 cm; body mass: 82.04 ± 13.61 kg; 1RM leg press: 339.86 ± 61.17 kg; 1RM leg extension: 121.71 ± 11.93 kg) were submitted to 9 weeks of RT with weekly sessions. Traditional (TRT) group (n = 12) performed three sets at 45° of leg press exercise at 75% of 1RM, PreEx group (n = 12) completed a set to failure on a leg extension machine prior to the leg press, and the control (CON) group (n = 7) did not train. Maximum strength, muscle thickness, and body composition were analyzed.

RESULTS

PreEx group increased in maximal strength on leg press (16 ± 8%) and leg extension (17 ± 11%), while the TRT group improved by 15 ± 9 and 11 ± 4%, respectively. The thickness of the quadriceps muscles increased for both intervention groups. Specifically, the post-training thickness of the vastus lateralis was significantly higher for PreEx (55%) compared to the CON group. The TRT group presented a greater loss of total and thigh fat mass when compared with the PreEx method. These results were found in the presence of a lower training load for the PreEx group.

CONCLUSION

The PreEx training can decrease the total training volume while maintaining results in strength and hypertrophy when comparing to TRT. However, TRT may be optimal if the goal is to decrease fat mass.

Calculating Set-Volume for the Limb Muscles with the Performance of Multi-Joint Exercises: Implications for Resistance Training Prescription

Resistance training volume, determined by the number of sets performed (set-volume) is considered one of the key variables in promoting muscle hypertrophy. To better guide resistance exercise prescription for weekly per-muscle training volume, the purpose of this paper is to provide evidence-based considerations for set-volume ratios between multi-joint (MJ) and single-joint (SJ) exercises so that practitioners can better manage prescription of training volume in program design. We analyzed this topic from three primary areas of focus: (1) biomechanical and physiological factors; (2) acute research; and (3) longitudinal research. From a biomechanical and physiological standpoint, when considering force production of different muscle groups, the moment arm of a given muscle, “motor abundance”, the link between biomechanics and exercise-induced fatigue, as well as the amount of time in voluntary muscle activation, a logical rationale can be made for SJ exercises producing greater hypertrophy of the limb muscles than MJ exercises (at least from specific exercises and under certain conditions). This would mean that sets for a MJ exercise should be counted fractionally for select muscles compared to an SJ exercise (i.e., less than a 1:1 ratio) when prescribing set-volumes for given muscles. When considering results from acute studies that measured muscle activation during the performance of SJ and MJ exercises, it seems that MJ exercises are not sufficient to maximize muscle activation of specific muscles. For example, during performance of the leg press and squat, muscle activation of the hamstrings is markedly lower than that of the quadriceps. These results suggest that a 1:1 ratio cannot be assumed. Current longitudinal research comparing the effects of training with MJ vs. SJ or MJ + SJ exercises is limited to the elbow flexors and the evidence is somewhat conflicting. Until more research is conducted to derive stronger conclusions on the topic, we propose the best advice would be to view set-volume prescription on a 1:1 basis, and then use logical rationale and personal expertise to make determinations on program design. Future research should focus on investigating longitudinal hypertrophic changes between MJ and SJ in a variety of populations, particularly resistance-trained individuals, while using site-specific measures of muscle growth to more systematically and precisely compute effective individualized set-volumes.