Athletes and recreational fitness enthusiasts, and people recovering from illness have many common goals (Fleck & Kraemer, 2014). For the athlete, the goals are generally driven by performance outcomes and for the fitness enthusiast health and wellness. However, what is clear many of the goals overlap. Depending on the individual’s training status and level of conditioning various training parameters will be appropriate for the benefits desired (Fleck & Kraemer, 2014; McArdle, Katch, & Katch, 2015).
Variables such as length of training period is important to desired results as initial training adaptation during the first four to six weeks is probably due to voluntary activation and not significant changes in muscle architecture (Beardsley, n.d.; McArdle, Katch, & Katch, 2015; Nuzzo, Barry, Jones, Gandevia, & Taylor, 2017). Although isometric, dynamic constant external resistance, variable resistance, variable-variable resistance, isokinetic, and eccentric training can provide significant benefits, not all are equal and not one is inclusive. Given the complexity of the factors involved with conditioning benefits and that much of research on resistance training has been short-term, direct application of research is somewhat difficult (Beardsley, n.d.; Fleck & Kraemer, 2014).
Strength development is complex. It can be viewed as the ability to apply force through the production of joint movements (Beardsley, n.d.). Many factors have been associated with the ability to apply and improve strength. Some of which may be myofilament packing density, voluntary activation (neural drive), antagonist coactivation, stabilizer activation, coordination, tendon stiffness, muscle cross-sectional area, muscle fascicle length, pennation angle, muscle moment arm length, and muscle fiber type (Beardsley, n.d.). Additionally, one’s genetic expression and foundation of development during formative years will impact the window of adaptation (Fleck & Kraemer, 2014).
Increases in strength can be achieved across all modes of strength training.
Isometric training improves strength via near-maximal isometric muscle actions (NMVMA) (Fleck & Kraemer, 2014). There is some indication that isometric maximal voluntary muscle actions (MVMA) may produce greater strength but this is still debated (Fleck & Kraemer, 2014). Apparently, the mechanism of strength production is dependent on time under tension. Explosive isometric training develops muscle contractile properties while slower sustained contractions directly impact nervous system development (Fleck & Kraemer, 2014). One purported mechanism for strength gains in isometric training is blood occlusion, as longer duration contractions seem to produce greater strength gains (Fleck & Kraemer, 2014).
The recommendations for healthy individuals is to perform isometric training 3 days per week with MVMA or NMVMA of three to five seconds in duration. Due to the joint angle specificity, it is recommended that the individual perform at joint angles increments of 10-30 degrees (Fleck & Kraemer, 2014). Isometric training is commonly used in early rehabilitation in which the therapist can manually monitor resistance and control for joint movement (Cameron & Monroe, 2007). It may be combined with other forms of resistance training to obtain specific outcomes such as working through a sticking point in a lift (Fleck & Kraemer, 2014).
The most common training modality for strength training is dynamic constant external resistance training (DCER). This form of training includes primarily concentric and eccentric muscle actions while acting against a constant force. Strength gains from DCER have been well documented across varied populations. Although strength gains have been found using many combinations of sets and repetitions and RM ranges (Fleck & Kraemer, 2014), this seems relative to initial fitness and training status (Beardsley, n.d.; Fleck & Kraemer, 2014). As with all strength training, gains become relatively smaller as one’s fitness improves with the largest gains seen during the initial stages of training in novices.
Based on the available data it appears that beginners would benefit from 1 to 3 days of total body weight training per week whereas intermediate and advanced lifters would benefit from 3-day total body or spilt routines 4 days per week and four to six days per week using a variety of split routines respectively. Intensity may range between 60 to 85 1RM for apparently healthy individuals. As an individual’s skill and fitness begin to advance and or they experience plateaus periodization is appropriate and beneficial.
Variable and Variable – Variable resistance training, like DCER produces strength gains using various set and repetition combinations. Isokinetic training, where muscular action is performed at specific velocities is beneficial to strength. As with other forms of resistance training, isokinetic training can improve strength applying a variety of sets, repetitions and in this case velocities with greater gains experienced with more than one set. There is a high degree of velocity specificity with strength improvement and isokinetic training and one should train at the velocity needed. However, there may be a strength carry-over training at intermediate speeds of 180-240 and 180 -210 degrees per second, above and below, for concentric and eccentric training respectively.
Finally, eccentric strength training can improve 1RM. Training eccentrically generally requires the individual to training in some form at supramaximal loads. The data supports that DCER eccentric training improves eccentric, isometric and concentric strength. The optimal eccentric resistance load may be 120% of 1RM. Although eccentric training is beneficial and safe, one must proceed slowly and with care as high incidence of delay-onset muscle soreness may occur.
Strength training has a beneficial effect on motor performance. A 2011 meta-analysis found that strength training had a beneficial effect on motor performance for children and adolescents in which a positive relationship was found with the intensity of training but not mode of training (Behringer, Heede, Matthews, & Mester, 2011). In a small 10-week study of women in a physical therapy environment, improvements in strength were positively associated with reaction time, tapping speed, and coordination (Kauranen, Siira, & Vanharanta, 1998). Resistance training also may improve motor performance during a 20-day bed-rest using isometric muscle actions (Shinohara, Yoshitake, Kouzaki, Fukuoka, & Fukunaga, 2003). Clearly, strength/resistance training has a broad application in relation to motor performance. However, strength in of itself is not a sole determinant of motor performance. Other factors such as neural drive, muscle fiber recruitment, fiber type, muscle stiffness, and increases in tendon stiffness may all play a role (Beardsley, n.d.).
Isometric strength has been demonstrated benefits in motor performance, but marginally (Hoffman, 2014). The highest association comes from activities that require isometric strength (Fleck & Kraemer, 2014). Isometric strength and dynamic motor performance have been questioned (Hoffman, 2014). Isometric strength and performance have a high degree of joint angle specificity (Hoffman, 2014), therefore, it is recommended that isometric actions take place at 10-20-degree intervals (Fleck & Kraemer, 2014).
Since most motor performance is dynamic and requires multiple joints it is further recommended that isometric actions should be tested against dynamic movements to assess carryover effects (Fleck & Kraemer, 2014). If implementing isometric training, the most ideal point (joint angle) to train may be the one needed that requires the greatest force generation during a dynamic movement.
DCER has been shown to improve motor performance. Like strength, changes are dependent on the initial fitness status of the subject with smaller gains made by people with higher fitness. Past training, type of program, and length of program are predictive of motor performance (Beardsley, n.d.). DCER associated with periodization seems to provide better results for motor performance (Beardsley, n.d.; Fleck & Kraemer, 2014). The DCER strength program should include all muscles in the activity targeted with attention to the weakest and as best as possible mimic the activity movement patterns for maximum results (Fleck & Kraemer, 2014).
Variable resistance training has conflicting results. Lever systems may outperform cam type systems in regards to power development (Fleck & Kraemer, 2014). However, it seems that a mix of training protocols, equipment selection, and what combination applied should be considered (Fleck & Kraemer, 2014). Isokinetic training can improve motor performance across varied populations. Data has demonstrated its application for athletes in various sports and older adults and activities of daily living (Fleck & Kraemer, 2014). In short, it appears that faster training velocities prove superior for motor performance (Fleck & Kraemer, 2014), but more research is needed. Eccentric training and improved motor performance is ambiguous (Fleck & Kraemer, 2014).
Hypertrophy & Body Composition
Isometric training can lead to significant hypertrophy. Larger duration muscle actions may produce greater results but this may be accumulated as a wide variety of training can intensities can be used. MVIA from 30-50% to 100% with set ranges of 2-6 to 1-3, and repetitions of 1 to 10, for low and high-intensity training may be used respectively. Greater range of motion may influence hypertrophy especially in untrained individuals (Beardsley, n.d.). Given this performing isometric actions at different joint angles may produce better results.
DCER training can improve hypertrophy. The data suggests that the training intensity and volumes are varied and specific to the initial level of conditioning and training status (Beardsley, n.d.). For example, it has been suggested that novice lifters training at an intensity of 70-85% of 1RM, 1-3 sets, 8-12 repetitions at 2 to 3 days per week (Heyward & Gibson, 2014). For advanced lifters, however, gains in hypertrophy can be seen at 70-100% of 1RM, 3-6 sets periodized, 4 to 6 days per week (Heyward & Gibson, 2014). For untrained individuals using both single joint and multi-joint exercises seem to enhance hypertrophy, the same association is not found in trained individuals (Beardsley, n.d.).
Concentric isokinetic training has not shown good results in regards to hypertrophy (Fleck & Kraemer, 2014). Due to the lack of eccentric work increases in muscle size are not significant (Heyward & Gibson, 2014). Concentric isokinetic actions have been demonstrated to increase muscle cross-sectional area (Fleck & Kraemer, 2014). Fast isokinetic eccentric training is more beneficial than slow velocity training (Fleck & Kraemer, 2014). Eccentric training can induce increases in muscle fiber cross-sectional area for both type I and II fibers. During eccentric DCER training at 120% 1RM performing 8 sets of 10 repetitions net protein synthesis has been demonstrated (Fleck & Kraemer, 2014).
Changes in body composition are more reflective of developing hypertrophy across all weight training modalities. The increases in lean mass is probably the major determinate in changes in body composition rather than significant fat loss (Fleck & Kraemer, 2014).
Beardsley, C. (n.d.). Strength. Retrieved from https://www.strengthandconditioningresearch.com/
Behringer, M., Heede, A. V., Matthews, M., & Mester, J. (2011). Effects of Strength Training on Motor Performance Skills in Children and Adolescents: A Meta-Analysis. Pediatric Exercise Science, 23(2), 186-206. doi:10.1123/pes.23.2.186
Cameron, M. H., & Monroe, L. G. (2007). Physical rehabilitation: Evidence-based examination, evaluation, and intervention. St. Louis, MO: Elsevier Saunders.
Fleck, S. J., & Kraemer, W. J. (2014). Designing resistance training programs (4th ed.). Champaign, IL: Human Kinetics.
Heyward, V. H., & Gibson, A. L. (2014). Advanced fitness assessment and exercise prescription (7th ed.). Champaign, IL: Human Kinetics.
Hoffman, J. (2014). Physiological aspects of sport training and performance (2nd ed.). Champaign, IL: Human Kinetics.
Kauranen, K. J., Siira, P. T., & Vanharanta, H. V. (1998). A 10-week strength training program: Effect on the motor performance of an unimpaired upper extremity. Archives of Physical Medicine and Rehabilitation, 79(8), 925-930. doi:10.1016/s0003-9993(98)90089-2
McArdle, W. D., Katch, F. I., & Katch, V. L. (2015). Exercise physiology: Nutrition, energy, and human performance (8th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
Nuzzo, J. L., Barry, B. K., Jones, M. D., Gandevia, S. C., & Taylor, J. L. (2017). Effects of four weeks of strength training on the corticomotoneuronal pathway. Medicine & Science in Sports & Exercise, 49(11), 2286-2296. doi:10.1249/mss.0000000000001367
Shinohara, M., Yoshitake, Y., Kouzaki, M., Fukuoka, H., & Fukunaga, T. (2003). Strength training counteracts motor performance losses during bed rest. Journal of Applied Physiology, 95(4), 1485-1492. doi:10.1152/japplphysiol.01173.2002