Ideal protein (PRO) intake is a topic of much debate in the fitness community as the benefits and recommended intakes can vary greatly depending on the source. Likewise, PRO needs can be considerably different depending on an individual’s baseline activity level, body mass, and goals. For instance, the current recommended daily intake (RDA) for PRO is a meager 0.8 g/kg of bodyweight (BW) per day for adults of all ages.
Yet, robust research has emerged indicating that PRO intakes far above this value (1.2 to 1.6 g/kg of BW per day) are more ideal for health in adults regardless of their training status. The benefits of a higher PRO diet include, enhanced muscle protein synthesis post-training, higher satiety, improvement of body composition to favor increased lean body mass, and reduced risk of obesity (Phillips et al.,2016).
All NASM-CPTs can benefit from taking these findings and applying it to their fitness methodologies.
SARCOPENIA
Sarcopenia is a disease process common in older adults which leads to a decrease in muscle strength, muscle mass, and diminished physical performance. The development of sarcopenia is highly correlated with increased risk of falls, fractures, and an overall loss of independence in older adults.
The condition is often diagnosed via the administration of a series of assessments aimed at evaluating body composition (i.e., Dual-energy X-ray absorptiometry or Bioimpedance Analysis) and muscle strength (hand-grip test or chair stand test). Severity of the condition is assessed via tests of physical performance (Ardeljan & Hurezeanu, 2020).
THE PROS OF A HIGHER PROTEIN DIET
Recently, more research has been conducted to assess the specific benefits of a higher PRO diet in older adults- specifically examining the preventative effect of a high PRO diet on the development of
sarcopenia.
Similarly, this phenomenon impacts post-menopausal women greatly. Declining levels ofestrogen and testosterone (which serve as anabolic hormones) coupled with low levels of physical activity and poor dietary intake of PRO can accelerate this decline in muscle strength, lean body mass, and physical performance.
It is common for women in this age group to seek the services of a fitnes professional with a goal of weight loss, oftentimes, explaining that her weight gain began around the onset of menopause. However, it is important to note that this cohort may also present with sarcopenic obesity which is defined as the presence of a high fat mass in the setting of an overall below average lean body mass.
Proper training and nutrition are critical for this cohort as many may simply attempt caloric restriction as a means of achieving a weight loss goal while muscle tissue reserves continue to dwindle (Maltais et al., 2009). The above referenced study seeks to examine the effect of a higher PRO diet on the physical function of a cohort of older post-menopausal women.
STUDY SUMMARY
STUDY DESIGN
Cross-sectional observational study
STUDY OVERVIEW
The study was conducted at the University of Connecticut Health Center in conjunction with Yale University. Study participants were recruited as part of three studies, the other two of which included supplementation with DHEA and fish oil.
The researchers evaluated dietary logs, baseline body composition readings, and assessments of physical performance and well-being to evaluate the potential benefits of a high PRO diet (greater than 0.8 g/kg/day) in post-menopausal women between 60 and 90 years old.
PARTICIPANTS
The participants included a cohort of 387 women ranging in age from 60 to 90 years old and self-described as community-dwelling and independent. Potential participants with a diagnosis of significant osteoporosis (or other diseases of bone metabolism) or with a life expectancy less than 2 years were excluded.
Comorbidities such as heart-disease, hypertension, mild osteoporosis, and osteoarthritis were present in 7 percent, 39 percent, 15 percent, and 27 percent, respectively. Likewise, 33 percent of the participants were classified as overweight and 23.5 percent were classified as obese.
METHODS
The participants underwent measurements of body composition analysis (via DEXA), hand-grip strength using a dynameter, and tests of physical performance including the Physical Performance Test (PPT) and the Short Physical Performance Battery (SPPB). Additionally, The Medical Outcomes Survey Short-form 8 (MOS SF-8) was given to the women as a measurement of well-being.
PRO intake was assessed via analysis of 4 days of dietary logs produced by the study participants after receiving instructions from a registered dietitian regarding the process of dietary recall and reporting. The participants were placed into either a low PRO or high PRO group based on average
PRO consumption over the 4-day period using a cut-off point of 0.8 g/kg/BW/day with above this figure being considered a high PRO intake and lower than this figure considered a low PRO intake.
Results regarding physical performance was modified to account for differences in BMI amongst the women in the study.
RESULTS
The average daily PRO consumption of all study participants was equal to approximately 1 g/kg/day with 97 participants consuming less than 0.8g/kg/day and 290 participants consuming greater than that amount. The average age and height of the women was the same in both groups, however, there were significant differences in BMI, body weight, and fat mass as these measures were higher in the low PRO group.
It is also noteworthy that overall caloric intake and other macronutrient intake (carbohydrates and fats) was considerably higher in the high PRO group versus the low PRO group (1,778 kcal/day versus 1,245 kcal/day), yet these women had lower BMIs and fat mass as compared to the high PRO group.
Overall, women in the lower PRO group scored lower on measures of physical performance than those in the high PRO group. For instance, women in the high PRO group were able to maintain a single leg stance for 15.3 seconds versus 11.2 seconds. Likewise, women in the low PRO group walked at a slower pace when compared to those in the high PRO group. Chair rise time, hand grip strength, and reports of quality of life were not significantly different between the two groups.
KEY FINDINGS
• Higher PRO intake was correlated to lower overall body weight and fat mass.
• Overall caloric intake was higher in the high PRO group, yet body composition measurements were more favorable when compared to the low PRO group.
• Participants in the high PRO group scored higher on most tests of physical performance when compared to their counterparts consuming a lower PRO diet.
• The rate of reported falls was the same in both groups, but the rate of fracture as the result of a fall was lower in the high PRO intake group.
CLINICAL APPLICATIONS
Generally, metabolic rate tends to decline in the aging population due to a decrease in overall activity and lean body mass (Bosy-Westphal et al., 2003). Yet, this decline in lean body mass can be attenuated with a higher PRO intake and resistance training. Resistance training regimens aimed at inducing muscle hypertrophy are most effective at improving health markers in older adults, however, in these cases PRO timing becomes critical as older adults are not as anabolically efficient as younger adults (Ihalainen et al., 2019).
Likewise, mounting evidence is suggesting that an RDA of 0.8 g/kg/day for older adults is insufficient for maintenance of lean body mass as well as overall health and well-being. Rather, recommended PRO intakes of 1.2 to 1.6 g/kg/day may prove more efficacious in improving strength, physical fitness, and longevity of independence in this population (Deer & Volpi, 2015).
Similarly, older adults tend to absorb and utilize nutrients less efficiently than their younger counterparts. It is critical that older adults consume a nutrient dense and calorically sufficient diet even though obesity may still be a concern. There is substantial risk for sarcopenia in this cohort and weight loss must be monitored very carefully and very low-calorie diets avoided (Institute of Medicine (US) Food Forum, 2010).
STUDY LIMITATIONS
The study authors indicated that there were several limitations to this study. First, the dietary logs did not evaluate the timing, quality, and source of the PRO. Likewise, it is possible that the study participants may not have had perfect dietary recall. This study can only demonstrate association, not causation as it is an observational study so it is possible that low physical performance could have led to low appetite and poor nutritional intake in the low PRO group.
CONNECTION TO PRACTICE AS AN NASM CERTIFIED PERSONAL TRAINER
It is common for a fitness professional to have a client load heavy in post-menopausal women seeking weight loss. It is important to provide these clients with resources and research aimed at providing them with appropriate dietary recommendations targeted at consuming nutrient dense foods and healthy eating patterns such as the National Institute on Aging versus being advised simply restrict caloric intake to achieve weight loss (National Institute on Aging, 2019).
These clients are better served by setting S.M.A.R.T (specific, measurable, attainable, realistic, timely) goals surrounding increasing physical activity and setting healthy eating habits as opposed to setting weight loss goals (Summerfield, 2016).
Muscle atrophy in later adulthood is due primarily to a decrease in satellite cell concentration, most prominently in the type II muscle fibers. Satellite cells are responsible for regeneration of muscle tissue. T
hese specialized cells have the capability to proliferate in the presence of heavy resistance training. Muscle hypertrophy is still possible, albeit more difficult, in older adults. Equally, the maintenance of type II muscle fibers can be important in retaining physical strength and independence in older adults (Verdijk et al., 2009). It is of equal importance that as a NASM Certified Personal Trainer, you have the skills to design a highly effective resistance training program for this population.
Older adults are still fully capable in training in the higher phases of the OPT model™ including phases 3, 4, and 5 (muscular development, maximum strength, and power). In fact, it may be advisable to progress post-menopausal women through the higher phases of strength training after successful completion of stabilization-endurance and strength-endurance phases and good movement patterns have been established (Clark et al., 2014).
Heavier resistance and power level training can aid in improving body composition, bone turnover, and overall strength in this cohort (Sims, 2016). Nevertheless, training is only part of the solution.
Nutritional intervention such as optimal PRO intake (1.2 to 1.6 g/kg/day) and optimal PRO timing (boluses of 20-40 g spread throughout the day) is necessary to achieve strength gains in older adults. The above referenced study adds to the mounting body of evidence indicating that a higher PRO intake over the current RDA of 0.8 g/kg/day may be advisable for older adults.
REFERENCES
Ardeljan, A. D., & Hurezeanu, R. (2020). Sarcopenia. PubMed; StatPearls Publishing.
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THE AUTHOR
