For many individuals, inactivity due to aging leads to a loss of physical conditioning which in turn can lead to loss of independent living. It is well documented that aerobic training and strength training improve cardiovascular conditioning, body fat, muscle mass, strength, functional independence and reduces the risk of diabetes, chronic diseases, falls, and fractures.
Focus of the Study: The aim of this study was to compare exercise intensity progression for resistance training and aerobic activity in older and young women undergoing an Exercise Training (ET) program.
The study population consisted of 33 physically inactive but healthy women, divided into a young group (YG; 20-35 years) and older group (OG; 61-75 years) which underwent physical exercise screening and exercise testing in order to participate in this Cardiovascular and Muscular Fitness program at the University of Sao Paulo. 1
The Resistance Training: To determine muscles strength and the initial workout load (weight) the women performed the 1 Repetition Maximum (1RM) after familiarization bouts and 2-5 days after the last exercise session. The 1RM was done on the following nine exercises using machines and free-weights: the bench press, leg press, seated row, knee curl, shoulder press, calf raise, biceps curl, triceps push-down, and abdominal. The resistances exercises consisted of 2 sets of 8-12 repetitions for each exercise.
The Aerobic Training: Aerobic exercise was performed at the beginning of each exercise session and consisted of 20 minutes of cycle ergometer at 65-75% of Heart Rate Reserve (HRR) followed by the resistance training exercises and flexibility. The women worked out two times per week for approximately 70 minutes total per session, for 13 weeks. Each session was monitored by an exercise specialist.
The Exercise Intensity Progression: The exercise intensity of the aerobic training was increased by 5% whenever the subjects had adapted to the workout load. The exercise intensity for the resistance exercises (RE) was 5-10% whenever the subjects had adapted to the workout load.
Primary Findings: The relative exercise intensity progression was similar in healthy young and older women during the 13 weeks of training. The exercise program promoted improvements in muscular strength and aerobic capacity that were similar between the 2 groups.
Specifics of the Results: Pre and post exercise muscle strength was lower in OG than in YG as might be expected. The ET promoted a 15-38% increase in the 1RM test, with no significant differences between the YG and OF except for a tendency (p=0.07) to a greater increase in the knee curl 1 RM test for the OG. These increases were enough for the OG to show postexercise muscle strength similar to YG pre-exercise muscle strength. At baseline the OG showed lower physical capacity and thus started with lower absolute workloads in almost all exercises but remember the relative workload was the same for both groups for RE at 60% of 1RM. Only the biceps curl exercise did not show significant difference in the initial absolute workload.
The maximal graded aerobic test was not performed after the ET however; the differences between the cycle-ergometer workloads from the first and last exercise session seem to indicate endurance improvement. A significantly greater workload increase in the OG (71.7 +/- 36.8%) vs. YG (49.3 +/- 21.1%) was observed.
Discussion: Although exercise recommendations for both young and older adults include aerobic, resistance, and stretching exercises, generally it has been suggested that older people should begin exercise training at a lower intensity than young people. The RE recommendation for older adults is to perform 1-3 sets of 10-15 repetitions for 2-3 weeks and in general slow down the progressions. Whereas for young adults, the RE recommendations are 1-3 sets of 8-12 repetitions and add overloads upon seeing the strength adaptations.
The exercise intensity progression method used in this study was found to be safe because no injuries, muscle damage, or major muscle pain were observed in the OG and YG during the entire 13 week study period.
Other food for thought: Dr. Miriam Nelson’s work with post menopausal women indicated that to increase bone mass, the resistance loads need to be 85% or higher. So as trainers, we need to re-think our starting point for exercise training for older adults. Do keep in mind this study screened for healthy adults with no musculoskeletal injuries, or impairments. Subjects were given a symptom limited cardiopulmonary test to further rule out the presence of coronary artery disease. The YG had no women on arterial hypertension drugs nor on medications for type II diabetes, whereas the OG did. Smokers and subjects taking any drug that could potentially influence the cardiovascular response to exercise (Beta-Blockers) were excluded from the study.
1 Ciolac,E.G., Brech G.C., and Greve J.M.D. Age Does Not Affect Exercise Intensity Progression Among Women, J Strength Cond Res 24 (10), 3023-3031.