Mitchell Fromm (UW-SP) and Bryan Stuettgen, MPT
Strength is a necessary component of daily living. Our bodies are designed to respond to stresses placed on them. The higher the activity level, provided adequate recovery, the more they will adapt to overcome those stressors. As we age it becomes increasingly important to maintain the recoverable level of stress that will promote growth and maintain strength to reduce injury and prevent muscle loss.
Need for Strength
Within the next 10-15 years, an estimated 30% of the US population will be elderly, putting them at greater risk of health problems and loss of function. The US National Center for Health Statistics reports the average person spends about 15% of their life in an unhealthy state due to disability, injury or disease occurring in old age (Hunter, 2004).
Age is a major contributing factor to the loss of musculature. At age 30 muscle breakdown begins to exceed muscle growth. At age 50 1% of total muscle strength can diminish annually and by age 65 the rate has been found to be around 3% per year (Kennis, 2013). This age-related loss of muscle contributes greatly to the risk of falling and injury as well as muscle strains and other injuries. Age-related strength loss is generally characterized by reduced muscle mass and strength and is manifested by preferential type II myofiber atrophy (Hunter, 2004, Van Roie 2013). It has been considered type II fibers are not able to be activated as well in older populations due to this atrophy and denervation. Type II muscle fiber type responds better to weight training for strength and power for growth and maintenance over type I which is characterized by its endurance properties.
There are multiple approaches to building strength. The muscle can advance by recruiting more of the available muscle through training. Weight lifting or similar activity teaches the muscle to recruit more of the available fibers that exist. To recruit and utilize muscle a nerve pathway must be available. Weight training also builds and improves this neuro-muscular connection allowing for more muscle fiber recruitment and better precision of movement. Another training goal could be hypertrophy or the enlargement of muscle. Creating more muscle allows for a larger pool of recruitment, which can lead to increased strength through training. Training cycles targeting both strength and hypertrophy should be included to maximally stimulate muscle fibers and best improve overall growth potential.
Power is lost at an even faster rate than strength. This loss is directly related to functional ability in daily living. A study by Pereira (2012) led to findings suggesting that training cessation up to 6 weeks is sufficient to induce significant losses in dynamic strength in 1RM (1 rep maximum weight). To some extent, functional capacity, and especially explosive force, may be preserved after high-speed power training. As the older population is more susceptible to detraining from missed activity due to injury or illness, power training should be considered when building an exercise program.
Loss of power generation may also be attributed to the lowered ability to create creatine-kinase during aging, a fuel the body creates and uses to generate power. Calcium release also decreases with age limiting the contraction-relaxation cycle of muscle, and inadequate protein has proven to limit growth potential as it is a staple of building and maintaining muscle. As they say, the temple cannot be created without the bricks. Detailing appropriate nutritional adaptations is outside of the scope of this paper, however, proper nutrition must be considered to achieve training adaptations and individual recommendations should be sought by a qualified trainer or nutritionist.
Strength in everyday life
Strength is a necessary component in the completion of daily tasks. Walking, maintaining an upright posture, and balance all have strength components where failure in any of the mechanisms may lead to compounding injuries. Motions beyond them such as bending, lifting, squatting, and transporting items have requisite strength requirements for completion without injury. The need for strength is apparent and crucial for those seeking to maintain their independence. Being able to complete tasks unaided reduces or eliminates the need for assisted living while reducing or eliminating those associated costs. Strength training extends the length of time a person is able to maintain independent motion barring other complicating factors.
Implementing strength training programs can have long-lasting effects. A long term strength study by Kennis (2013) found that increases in muscle strength and muscle power after a 1-year strength-training intervention theoretically can compensate for age-related losses over 3 to 5 years. Moreover, 7 years after their enrollment in the study, participants of the {strength training intervention} group experienced a significantly lower loss in basic strength compared with the {control} group.
Protocol
Muscle reductions from age are found to be due to multiple factors. Training both the nervous system as well as targeting the muscle fibers are necessary for a successful strength program. It is commonly accepted that strength training should be conducted by lifting above 80% of the 1 rep maximum with sets of 6 or fewer repetitions, and hypertrophic training with weights between 67-80% for sets of 6-12 repetitions. Though these current standards are accurate for those goals, they are not entirely definite and certainly are not exclusive. Studies conducted and compiled by Van Roie (2013) have examined the growth ability utilizing low weight high rep protocols and found hypertrophy was achievable when the training sessions achieved momentary muscular failure. Henneman's size principle of motor unit recruitment indicates that, when a submaximal contraction is sustained, initially recruited motor units will fatigue, creating the need to additionally activate larger motor units. When the exercise is repeated to the point of muscle failure, (near) maximal motor unit recruitment will occur, regardless of the external resistance used (Van Roie, 2013). Expanding on this, one study was conducted in which a highly fatiguing protocol of 60 repetitions at 20–25% of 1RM was immediately followed (no rest) by a set of 10 repetitions at 40% of 1RM. This mixed low-resistance exercise protocol showed interesting benefits on the dynamic strength and speed of movement of the knee extensors (Van Roie, 2013). Those studies further showed promising results on speed of movement at different resistances, even though training was performed at a moderate speed.
Studies conducted by Schoenfeld et al (2016, 2017) led to findings indicating that maximal strength benefits are obtained from the use of heavy loads while muscle hypertrophy can be equally achieved across a spectrum of loading ranges. This is backed by Dr. Mike Israetel when explaining the time under tension can be equal across a range of weights, so long as the muscle fibers are brought close to or achieve fatigue. As long as all three components (concentric, isometric, eccentric) of the working muscle are achieved through the majority of the range of motion, muscular gains have been found utilizing as little as 30% of the 1RM. Schoenfeld’s studies contrasted volume with the analysis using binary frequency as a predictor variable revealed a significant impact of training frequency on hypertrophy effect size (P = 0.002), with the higher frequency being associated with a greater effect size than lower frequency (0.49 ± 0.08 vs. 0.30 ± 0.07, respectively).
Methods such as these or bodyweight protocols are effective for those who are adverse to weight training or unable to due to contraindications, however, volume was the decisive factor in how much could be achieved wherein multiple sessions per week were superior to a single intense session. Factors that must be considered when using any program or weight is the proper form and control. Utilizing improper body mechanics can put extreme stress on the joints and swinging weights around with momentum often relates to injury. It is paramount to only use weights that can be used in a controlled fashion. This will not only lessen or eliminate an injury risk but subsequently result in better muscular growth as each phase of the muscle contraction and lengthening phases are used appropriately through the entire lift. Especially in newer lifters, this means that using a lighter weight for more repetitions is the most appropriate choice. For experienced lifters, incorporating light-weight can allow for an increase in total volume, leading to additional strength gains and improving muscular endurance. This approach also trains the nervous system to achieve precise motion to achieve a better neuro-muscular improvement.
It can be overwhelming to begin a strength program with a vast amount of information that seems to be ever-changing. Experts exist in these areas to assist in setting and reaching goals. Personal trainers specialize in strength and conditioning while ensuring proper form to prevent injury. When choosing a personal trainer be alert to their credentialing as the field is largely unregulated and there are “internet experts” who claim experience they may or may not have. Physical therapists are experts in the non-surgical treatment of injuries or conditions. As such they are great assets in program creation while considering prevention and treatment of injuries, especially for those with a prior history of injury. Both the physical therapist and personal trainer should have a great working knowledge of anatomy and physiology which is critical for accurate and individualized program creation. They often work together for the best possible patient outcome.
Overall
The need to maintain strength training is clear. It is highly transferable to everyday life, the amount of which will be directly affected by the effort put into training and the program design. Multiple programs can be implemented to retain strength, but the secondary and tertiary effects of training must be considered for the best individual approach. The coach-client relationship should not be overlooked as it is often the largest contributing factor determining compliance and exertion in training, as any properly implemented program will have benefits over the stagnation of not completing any program at all.
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Hunter GR, Mccarthy JP, Bamman MM. Effects of Resistance Training on Older Adults. Sports Medicine. 2004;34(5):329-348. doi:10.2165/00007256-200434050-00005.
Kennis E, Verschueren SM, Bogaerts A, Roie EV, Boonen S, Delecluse C. Long-Term Impact of Strength Training on Muscle Strength Characteristics in Older Adults. Archives of Physical Medicine and Rehabilitation. 2013;94(11):2054-2060. doi:10.1016/j.apmr.2013.06.018.
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