Strength training: how does movement affect your workout?

The extent of guided movement over a joint is defined as the extent of movement. Mechanical force generation in the muscle is provided by the sarcomere, the smallest contractile unit. The sarcomere itself is composed of actin and myosin filaments. These filaments slide into each other, and the cross bridges formed at the molecular level between actin and myosin are responsible for generating force. When a sarcomere is short, the degree of overlap between actin and myosin is small and little cross-bridging and strength can be built. As overlaps increase, more transverse bridges and force can be built up until an optimum is reached at intermediate sarcomere length (about 2.6 - 2.8 µm), which then decreases as sarcomere length increases [1]. This relationship is also known as the force-length relationship.

The force-length relationship is one of the reasons why you can’t generate the same amount of force at every joint angle position.

A controversial topic

Academic literature is divided on whether a partial or full range of motion is optimal for increasing muscle mass. It’s believed that repetitions over the full range of motion maximise mechanical load over the entire muscle fibre area, stimulating hypertrophy more than partial range of motion [3]. On the other hand, the use of a partial range of motion allows for an increase in external load, as repetitions are performed at an optimal force-length ratio and thus can induce greater hypertrophic adaptations [4].

Studies in favour of full extent of movement

McMahon et al. [5] investigated the relationship between exercise magnitude during strength training and hypertrophy, subcutaneous fat, and strength. 26 recreationally active participants (19.6 ± 2.6 years) were divided into a full range of motion group (0° - 90°) and a partial range of motion group (0° - 50°), undergoing strength training three times a week for 8 weeks followed by a 4-week break. Their training consisted of lower limb exercises at 80% 1-RM intensity. Compliance with the appropriate knee angle was checked using a so-called goniometer. The m. vastus lateralis volume was measured by ultrasound at different locations (i.e. 25%, 50%, and 75% of the length of the femur).

A significant increase in muscle mass was observed in both groups, compared to the baseline. With a full range of motion, there was a trend toward greater muscle gain at all measured sites compared to the group that trained using only a partial range of motion. This was statistically significant when measured at 75% femur length after 8 weeks. The authors concluded that from a practical point of view, a full range of motion should be aimed for in strength training if the goal is to increase muscle strength and size. In addition, extent of movement shouldn’t fall victim to a greater external load.

Pinto et al. [6] compared partial to full extent of movement in relation to strength and hypertrophy in young men. Participants were randomly divided into 3 groups:

• full range of motion (0° - 130°, 0° = full elbow extension).
• partial range of motion (50° - 100°).
• control group.

Subjects (21.7 ± 3.5 years, n = 40) exercised 2 days per week for 10 weeks. Elbow flexor (biceps) strength was assessed by 1-RM and muscle growth was assessed by ultrasound. Both groups significantly increased their elbow flexor strength. Following the test, strength was significantly greater in the full range of motion group than in the partial range of motion group. Average hypertrophy of elbow flexors increased significantly in both training groups. The authors concluded that strength and hypertrophy can be elicited by training with both full and partial range of motion, with a full range of motion resulting in greater improvements in strength than a partial range of motion.

A similar conclusion was reached by Bloomquist et al. [7], who investigated the manipulation of squat movement magnitude and the resulting adaptations. Seventeen male participants (24.0 ± 4.5 years) were randomly assigned to 12 weeks of squat training with full (0° - 120°) or partial range of motion (0° - 60°). Strength was measured by 1-RM and the cross-sectional area of the muscles was examined by magnetic resonance imaging. Both protocols produced a significant increase in strength compared to the baseline measurement. However, training over the full range of motion resulted in significantly greater muscle gain in the anterior thigh musculature compared to the partial range of motion group.

Studies in favour of partial extent of movement

Contrasting results to the above studies were obtained by Valamatos and colleagues [8], who studied the effects of a 15-week partial range of motion workout on the architecture and mechanical properties of the m. vastus lateralis (lateral thigh muscle). To do this, they recruited 19 untrained male participants (24.1 ± 4.4 years) and randomly assigned them to a control or training group. Seventeen male participants (24.0 ± 4.5 years) were randomly assigned to 12 weeks of squat training with full (0° - 100°) or partial range of motion (0° - 60°). Strength training over the full range of motion changed the length of muscle fibre bundles and specific tension. Partial range of motion had a moderate effect on muscle cross-sectional area and force. The authors concluded that muscle adaptations are dependent on the extent of movement, as the length of muscle fibre bundles and specific tension increase with greater extent of movement. Conversely, a partial measure of motion is associated with angle-specific force adaptations.

A recent systematic review concluded that muscle length matters during isometric training, as training longer muscles was shown to stimulate hypertrophy to a greater extent than isometric training for shorter muscles. This suggests that partial and full range of motion training is equally effective when partial training is performed for longer muscles [9]. In contrast, other studies reported no statistically significant difference in terms of hypertrophy when comparing partial and full range of motion [5,6].

Goto et al [10] investigated whether partial exercise extent is effective in inducing muscle hypertrophy and function. They hypothesised that a partial range of motion would result in higher vascular occlusion due to higher muscular tension and constant contractions, which could lead to an increase in hypertrophy and strength. Therefore, 44 men (20-22 years) were recruited and divided into a partial range of motion group (45°- 90°) and a full range of motion group (0°- 90°), with elbow extensor training three times per week for 8 weeks. Participants had to complete 3 sets of 8 repetitions in each training session. For both groups, an increase in the cross-sectional area of the m. triceps brachii was observed by ultrasound, and an increase in isometric strength was noted. The cross-sectional area in the partial range training group was significantly larger than in the group that trained over the full range of motion.

Conclusion

In summary, working out over the full range of motion appears to be more beneficial for the induction of hypertrophy compared to training over the partial range of motion. However, if training over a partial range of motion, the focus should be on longer muscles. Individuals with musculoskeletal problems that result in a decreased range of motion could benefit here.

References

1. Gordon AM, Huxley AF, Julian FJ. The variation in isometric tension with sarcomere length in vertebrate muscle fibres. J Physiol. Wiley-Blackwell; 1966;184: 170–192. doi:5921536
2. Zoladz JA. Muscle and exercise physiology. Muscle and Exercise Physiology. Elsevier; 2018. doi:10.1016/C2017-0-01877-3
3. Fleck SJ, Kraemer WJ. Designing Resistance Training Programs. 3rd ed. Champaign, IL: Human Kinetics. 2004.
4. Sisco P, Little JR. Power factor training a scientific approach to building lean muscle mass. Chicago: Contemporary Books; 1997.
5. McMahon GE, Morse CI, Burden A, Winwood K, Onambélé GL. Impact of range of motion during ecologically valid resistance training protocols on muscle size, subcutaneous fat, and strength. J Strength Cond Res. 2014;28: 245–255. doi:10.1519/JSC.0b013e318297143a
6. Pinto RS, Gomes N, Radaelli R, Botton CE, Brown LE, Bottaro M. Effect of range of motion on muscle strength and thickness. J Strength Cond Res. 2012;26: 2140–2145. doi:10.1519/JSC.0b013e31823a3b15
7. Bloomquist K, Langberg H, Karlsen S, Madsgaard S, Boesen M, Raastad T. Effect of range of motion in heavy load squatting on muscle and tendon adaptations. Eur J Appl Physiol. Springer; 2013;113: 2133–2142. doi:10.1007/s00421-013-2642-7
8. Valamatos MJ, Tavares F, Santos RM, Veloso AP, Mil-Homens P. Influence of full range of motion vs. equalized partial range of motion training on muscle architecture and mechanical properties. Eur J Appl Physiol. Springer Berlin Heidelberg; 2018;118: 1969–1983. doi:10.1007/s00421-018-3932-x
9. Oranchuk DJ, Storey AG, Nelson AR, Cronin JB. Isometric training and long-term adaptations: Effects of muscle length, intensity, and intent: A systematic review. Scand J Med Sci Sport. Blackwell Munksgaard; 2019;29: 484–503. doi:10.1111/sms.13375
10. Goto M, Maeda C, Hirayama T, Terada S, Nirengi S, Kurosawa Y, et al. Partial range of motion exercise is effective for facilitating muscle hypertrophy and function through sustained intramuscular hypoxia in young trained men. J Strength Cond Res. NSCA National Strength and Conditioning Association; 2019;33: 1286–1294. doi:10.1519/JSC.0000000000002051