Scholarly article on topic 'Women and exercise in aging'

Women and exercise in aging Academic research paper on "Health sciences"

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{Aerobic / "Exercise prescription" / Flexibility / "Older adults" / "Strength training"}

Abstract of research paper on Health sciences, author of scientific article — Kristina L. Kendall, Ciaran M. Fairman

Abstract Aging is associated with physiological declines, notably a decrease in bone mineral density (BMD) and lean body mass, with a concurrent increase in body fat and central adiposity. Interest in women and aging is of particular interest partly as a result of gender specific responses to aging, particularly as a result of menopause. It is possible that the onset of menopause may augment the physiological decline associated with aging and inactivity. More so, a higher incidence of metabolic syndrome (an accumulation of cardiovascular disease risk factors including obesity, low-density lipoprotein cholesterol, high blood pressure, and high fasting glucose) has been shown in middle-aged women during the postmenopausal period. This is due in part to the drastic changes in body composition, as previously discussed, but also a change in physical activity (PA) levels. Sarcopenia is an age related decrease in the cross-sectional area of skeletal muscle fibers that consequently leads to a decline in physical function, gait speed, balance, coordination, decreased BMD, and quality of life. PA plays an essential role in combating physiological decline associated with aging. Maintenance of adequate levels of PA can result in increased longevity and a reduced risk for metabolic disease along with other chronic diseases. The aim of this paper is to review relevant literature, examine current PA guidelines, and provide recommendations specific to women based on current research.

Academic research paper on topic "Women and exercise in aging"

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Available online at www.sciencedirect.com

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Journal of Sport and Health Science xx (2014) 1—9

Review

Women and exercise in aging

Kristina L. Kendall*, Ciaran M. Fairman

Department of Health and Kinesiology, Georgia Southern University, Statesboro, GA 30458, USA Received 22 October 2013; revised 29 January 2014; accepted 17 February 2014

www.jshs.org.cn

Abstract

Aging is associated with physiological declines, notably a decrease in bone mineral density (BMD) and lean body mass (LBM), with a concurrent increase in body fat, and central adiposity. Interest in women and aging is of particular interest partly as a result of gender specific responses to aging, particularly as a result of menopause. It is possible that the onset of menopause may augment the physiological decline associated with aging and inactivity. More so, a higher incidence of metabolic syndrome (an accumulation of cardiovascular disease risk factors including obesity, low-density lipoprotein cholesterol (LDL-C), high blood pressure, and high fasting glucose) has been shown in middle-aged women during the postmenopausal period. This is due in part to the drastic changes in body composition, as previously discussed, but also a change in physical activity (PA) levels. Sarcopenia is an age related decrease in the cross-sectional area of skeletal muscle fibers that consequently leads to a decline in physical function, gait speed, balance, coordination, decreased BMD, and quality of life. PA plays an essential role in combating physiological decline associated with aging. Maintenance of adequate levels of PA can result in increased longevity, and a reduced risk for metabolic disease along with other chronic diseases. The aim of this paper is to review relevant literature, examine current PA guidelines and provide recommendations specific to women based on current research.

Copyright © 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved. Keywords: Aerobic; Exercise prescription; Flexibility; Older adults; Strength training

1. Introduction

It is anticipated that there will be almost 89 million people 65 years old or above by the year 2050.1 As the number of elderly people worldwide increases,2 interest in health related outcomes of aging has concurrently increased. It has been suggested that an age-associated decline in physical function, cardiorespiratory fitness, and muscle mass may accelerate the physiological decline in later decades of life3 and lead to an increase in morbidity and mortality rates.2,4

Women are of particular interest due to some gender differences accompanying aging, particularly as a result of menopause. Physiological decline, particularly a reduction in bone mineral density (BMD) can be attributed to estrogen deficiency as a result of menopause.5 Reductions in BMD put older women at risk for osteoporosis which can lead to balance and gait issues, a higher risk of injury, subsequent financial costs,6 and even a higher risk of mortality.2 More so, a decrease in muscle strength in combination with reduced BMD can further impair balance and mobility, leading to a decline in functional capacity.7 Thus, it becomes apparent of the need for resistance training to attenuate the decline in lean mass, muscle mass, and BMD that accompany aging and inactivity. Other physiological changes that occur with aging are alterations to the cardiovascular (CV) system, which can further impair functional capacity. Remarkably, by the age of 75 years, more than half of the functional capacity of the CV system has been lost,8 leading to VO2max values lower than that which is required for many common activities of daily

2095-2546/$ - see front matter Copyright © 2014, Shanghai University of Sport. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/jjshs.2014.02.001

* Corresponding author.

E-mail address: kkendall@georgiasouthern.edu (K.L. Kendall) Peer review under responsibility of Shanghai University of Sport

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living.9 More than just leading to decreases in quality of life, low cardiorespiratory fitness has been associated with CV disease and all-cause mortality.10-12 The CV system remains adaptable at any age,13'14 with relative increases in VO2max in older populations equivalent to those seen in younger individuals.

Physical activity (PA) has long been associated with the attenuation of physical decline associated with aging.15 The purpose of this article is to:

1. Examine the decline in physiological variables associated with aging and a sedentary lifestyle.

2. Review recent research investigating exercise interventions on health related components in women.

3. Provide recommendations for PA that builds on prior research and guidelines to improve physiological functioning in aging women.

2. Physiological decline with aging and inactivity

Aging is associated with physiological declines, notably a decrease in BMD and lean body mass (LBM), with a concurrent increase in body fat and central adiposity.16'17 It is possible that the onset of menopause may augment the decline in physiological decline associated with aging and inactivity.5 Wang and colleagues18 compared almost 400 early postmenopausal women and found higher levels of total body fat, as well as abdominal and android fat in postmenopausal women. Consequently, the authors could not conclude that the changes in body fat were related to menopause or merely a result of aging alone. The authors did note, however, that changes in fat-free mass (FFM), including bone mass, may be attributed to menopause-related mechanisms, including

deficiencies in growth hormones and estrogen. Douchi et al. had similar findings when comparing body composition variables between pre- and post-menopausal women. The authors demonstrated an increase in percentage of body fat (30.8% ± 7.1% vs. 34.4% ± 7.0%), trunk fat mass (6.6 ± 3.9 kg vs. 8.5 ± 3.4 kg), and trunk-leg fat ratio (0.91 ± 0.4 vs. 1.3 ± 0.5) with aging. Concurrently, they found that lean mass (right arm, trunk, bilateral legs and total body (34.5 ± 4.3 kg vs. 32.5 ± 3.96 kg)) also declined with age. Baker and colleagues19 found that females had a greater decline in BMD with age compared to males. More so, a higher incidence of metabolic syndrome (an accumulation of cardiovascular disease risk factors including obesity, low-density lipoprotein cholesterol (LDL-C), high blood pressure, and high fasting glucose) has been shown in middle-aged women during the postmenopausal period. This is due in part to the drastic changes in body composition, as previously discussed, but also a change in PA levels. In a longitudinal study of over 77,000 (34e59 years) women spanning 24 years, van Dam et al.20 found high body mass index (BMI, 25+) and lower levels of PA (<30 min/day of moderate to vigorous intensity activity) to be attributed with a higher risk of CV disease, cancer, and all-cause mortality. Furthermore, Sisson et al.21 found higher levels of sedentary behavior (<4 h/day) associated with a 54% increase in risk for metabolic syndrome only in those women not meeting national guidelines.

Sarcopenia, is an age related decrease in the cross-sectional area of skeletal muscle fibers that consequently leads to a decline in physical function, gait speed, balance, coordination, decreased bone density, and quality of life.22 Additionally, due to lower levels of vigorous activity, aging populations experience notably higher losses in type II fibers than type I fi-bers,23 which can reduce strength, speed, power, and overall PA. Subsequently, maintenance of muscle mass and strength is

Table 1

Physiological changes and health benefits associated with different modes of activity.8

Training system

Cardiovascular training

Resistance training

Flexibility

Examples of exercises Physiological changes Potential health benefits

Walking [Capillary density [Aerobic power

Running [Mitochondrial density [ Ability of body to deliver oxygen and

Dancing [Myoglobin content nutrients to working muscle

Soccer [Immune function [ Muscular endurance

Swimming Y Heart rate [ Ability to perform activities

Basketball Y Blood pressure of daily living

[Ligament strength [ Delay of fatigue

[ Tendon strength [ Physical function

Y Body fat % Y Risk of breast & colon cancer

[Enzyme activity Y Risk of type 2 diabetes Y Coronary heart disease

Weight training [ Muscle girth [ Strength

Aquatic weight training [Muscle fiber size [ Balance

[ Contractile proteins [ Posture

Y Body fat % Y Risk of osteoporosis

Y Mitochondrial density YRisk of falls

[Strength and power Y Risk of injury

[ Bone mineral density [ Physical functioning

[ Size and strength of tendons

Stretching exercises [ Elasticity of tendons [ Range of motion

Doorway stretch [ Ability to perform activities

Hamstring stretch of daily living

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imperative to maintaining a high quality level of physical functioning, and attenuate measures of frailty. Muscular adaptations to exercise (increase in muscle size, cross-sectional area, and consequent strength) may counteract muscle loss and physical decline associated with sarcopenia.

Thus it appears that PA plays a pivotal role in the attenuation of physical decline and can potentially improve physical functioning and quality of life with age.24,25 Furthermore, maintenance of adequate levels of PA can result in increased longevity, and a reduced risk for metabolic disease along with other chronic diseases. A list of physiological changes associate with different modes of activity and their potential health outcome are listed in the Table 1.26_28

3. CV exercise

CV disease is the major cause of death in older wom-en.29_31 It therefore becomes of utmost importance to decrease the risk for CV disease. Cross-sectional and intervention studies have repeatedly shown that endurance training

32,33 34

can improve insulin sensitivity,32,33 lower blood pressure,34

35_37 36_38

improve lipid profiles, and decrease body fat, all factors related to CV disease. Furthermore, aerobic exercise has been shown to increase maximal oxygen consumption (VO2max), an index of cardiorespiratory fitness that on average decreases 5%_15% per decade after the age of 25.39 These physiological responses to aerobic exercise results in an increased efficiency of the system during exercise (increase stroke volume, capillary, and mitochondrial density, lower heart rate and blood pressure) and ability to better deliver oxygen and glucose to working muscles.40

In an investigation into the level of activity that may protect against CV disease mortality, Hamer and Stamatakis41 recruited 23,747 men and women without a known history of CV disease at baseline. The researchers tracked PA levels and causes of death over a period of 7.0 ± 3.0 years. By calculating a hazard ratio (HR), the authors found that a minimum of two sessions of moderate to vigorous PA per week was associated with a reduced risk of CV disease and all-cause mortality. Compared to active adults, those individuals who were inactive were at elevated risk of CV disease (HR of 1.41 vs. active: HR of 0.82) and all-cause mortality (HR of 1.50 vs. active: HR of 1.11). Supporting these findings, several studies have demonstrated walking, or walk_jogging, for 30_60 min, 2_5 days per week can significantly decrease body weight, increase BMD and VO2max, and improve glucose levels in older women.42_45

Although reaching current recommended PA levels (30 min of moderate activity 5 days/week, or 20 min vigorous activity 3 days/week) is sufficient for partially reducing risk factors for CV disease, it does not eliminate the additional risk that overweight/obesity poses.46 Thus increasing levels of PA in order to improve body composition may further reduce the risk of CV disease and mortality. Martins et al.47 found that 16 weeks of aerobic training for 45 min, 3 days per week, progressing from 40% to 50% HR reserve to 71%_85% HR reserve significantly improved waist circumference (pre:

93.3 ± 9.9 cm, post: 90.0 ± 8.6 cm), in addition to upper body strength (number of arm curl repetitions in 30 s (pre: 15 ± 4, post: 20 ± 5)), lower body strength (number of chair stand repetitions in 30 s (pre: 12 ± 4, post: 18 ± 4)) and aerobic endurance, as measured by a 6-min walk test (pre: 380 ± 75 m, post: 438 ± 85 m). Sixteen weeks after the cessation of the training program, BM, LDL, and C-reactive protein (CRP) were significantly lower than baseline values (BM: 73.1 mg/L, 11.9 kg vs. 72.2 mg/L, 11.4 kg; LDL: 79.8 ± 32.0 mg/dL vs. 55.3 ± 17.6 mg/dL; CRP: 3.38 ± 1.48 mg/L vs. 1.39 ± 1.35 mg/L). This highlights the need to gradually progress the intensity of aerobic training over time to allow for adequate metabolic adaptations to occur.

Evaluating different modalities for aerobic training, Boca-lini et al.48 compared the effects of land (LE) versus water-based (WE) aerobic exercise in sedentary older women over the course of 12 weeks (3 days/week at ~70% of age-predicted HRmax). Although VO2max, lower body strength, and agility significantly improved in both groups, only the WE group saw a significant decrease in resting HR (pre: 92 ± 2 bpm, post: 83 ± 3 bpm), a significant increase in upper body strength (arm curl test, pre: 17 ± 3 reps, post: 25 ± 1 reps), and improved markers of flexibility, both lower body (sit-and-reach, pre: 24 ± 3 cm, post:36 ± 2 cm) and upper body (back scratch, pre: —10 ± 2 cm, post: —6 ± 2 cm), suggesting its use as an alternative to traditional aerobic training. More so, walking in conjunction with other aerobic exercise forms, such as swimming, cycling, or dancing, resulted in improve VO2max and blood pressure,49 favorable changes in lipids,49 and improved muscle strength and endurance, flexibility, and balance.39

4. Strength training

After the age of 30, a decrease in muscle size and thickness, along with an increase in intramuscular fat takes place.50 The loss of muscle mass, resulting from a decreased number of muscle fibers and atrophy of remaining muscle fibers (sarco-penia), has a strong role in the loss of strength, as well as the ability to perform activities of daily living.51,52 The decline in isometric and dynamic muscle strength is a consequence of the aging process, with approximately 30% of strength lost between the ages of 50 and 70 years.53 Furthermore, cross-sectional data suggests that muscle strength declines by approximately 15% per decade in the 6th and 7th decade, and 30% thereafter.54_57 Resistance training (RT) has increased its popularity among older adults because of it benefits on muscle fitness, body composition, mobility, and functional capacity. More so, regular RT can offset the typical age-associated decline in bone health by maintaining or increasing BMD and total body mineral content.58

Although there is little question as to the benefits of RT in an older population, there is still some disparity regarding the ideal training volume (i.e., number of sets, reps, and load).59,60 Previous research has shown that older women who resistance train intensely (HR-80% 1-RM) three times per week (whole-body resistance training, including elbow flexion and

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Table 2

PA interventions in postmenopausal women with health related fitness outcomes.28 Adapted with permission.

Groups

N (Mean age)

Mode of exercise and duration of study

Training prescription

Main results

Asikainen et al.42'91

2 Ex: Ex1, Ex2 and CTL, stratified by HRT

134 (57 years)

Asikainen et al.43'91

4 Ex: Ex1-4 and CTL, stratified by HRT

Brooke-Wavell et al.44 EX, CTL 84 (64 years)

Busby et al.92 EX, disc., EX + disc., CTL 50 (52 years)

Hopkins et al.81 EX, CTL 65 (65 years)

King et al.93

Ready et al.94

Shinkai et al.95 Bravo et al.80

Chow et al.96

Irwin et al.97 Bemben et al.98

3 EX: HIG, HIH, LIH, CTL

2 EX: 3 days/week, 5 days/week, CTL

EX + Diet, CTL

EX, CTL stratified by age and etionate and HRT

A, A + S, CTL

EX, CTL

2 EX: high load, high rep and CTL, stratified by BMD

Walking 15 weeks

121 (55 years)

160 (57 years)

79 (61 years)

32 (54 years) 142 (60 years)

10 (56 years)

173 (61 years) 35 (51 years)

Walking 4 weeks

Walking

1 year

Walkingejogging 12 weeks

Aerobic dance and stretching 12 weeks

Walking, jogging, cycling, treadmills 1 year Walking 24 weeks

Cycling, walking, jogging, swimming 12 weeks Walking, aerobic dancing, resistance EX

(wrist weights, elastic tubes), flex coordination EX 1 year

Walking, jogging, dancing, resistance EX, (wrist and ankle weights) 1 year Walking, cycling, strength training 1 year Strength training (Cybex) 24 weeks

30-60 min, 65% VO2max ir (Ex1) or two (Ex2) daily session, 5 days/week

54 min, 55% VO2max (Ex1) 65 min, 45% VO2max (Ex2) 38 min, 55% VO2max (Ex3) 46 min, 45% VO2max (Ex4) 5 days/week

20 min self-selected pace

30 min, 60%-73% VO2max

15 min warm-up, 20 min low-impact EX, 15 min cool-down 3 days/week

40 min, 73%-88%VO2max, 3 day/week; 30 min 60%-73% VO2max, 5 days/week

60 min 60% VO2max, 3 or 5 days/week

45-60 min, 50-60% VO2max, 3-4 days/week

10 min warm-up and flex

EX; 25 min, aerobic

training, 54%-69% VO2max; 15 min

EX for upper limbs

and trunk, 12-15 maximal rep;

5 min EX for flex

and coordination 3 days/week

30 min, 73% VO2max (A, A + S);

10-15 min of limb

and trunk EX, 10-RM, 10 rep

(A + S), 3 days/week

45 min, 75% VO2max, 3 days/week

12 EX, 80% 1-RM with 8 rep (high load) or 40% 1-RM with 16 rep, 3 sets, 3 days/week

Improvement in VO2max (2.5 mL/kg/min

(Ex1, Ex2), improvement in

diastolic BP —3 mmHg

(combined Ex1, Ex2), glu —0.21 mmol/L

(Ex1), —0.13 mmol/L (Ex2), weight —1.2 kg

(Ex1), —1.1 kg (Ex2), F% —2.1%

(EX1), —1.7% (EX2)

Improvement in VO2max (+2.9 mL/kg/min (EX1), +2.6 mL/kg/min (EX2), +2.4 mL/kg/min (EX3), +2.2 mL/kg/min (EX4)) and F% (—1.2% (EX1), —1.1% (EX2), —0.6% (EX3), —1.0% (EX4)) Increased BMD (EX +0.2, CTL —2)

Improved VO2max (4% in EX, 6% in disc. Group)

Increased aerobic fitness (17%), strength/endurance (62%), flex and balance (12%)

Increased VO2max (1.5-2.3 mL/kg/min)

Improved VO2max (12% (3 days/week), 14% (5 days/week)), weight (—0.6 kg, 3 days/week), and F% (—4.2% (3 days/week), —4.0% (5 days/week)) Decreased body mass (—6%) and F% (—10%)

Improved strength (15%) and half-mile walk time (—9%)

Improved bone mass (4%-7% in A + S) and VO2max (22% in A, 32% in A + S)

Decreased weight (—1.4 kg) and F% (—1%), increased VO2max (11%) Increased muscle strength (20%-40%)

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extension, seated row, overhead press, leg extension and leg curl, bench press, and sit ups) have similar improvements in fat-free mass and total body strength. Hunter and colleagues61 demonstrated a 1.8 kg increase in FFM for the HR group, compared to an increase of 1.9 kg for the VR group. Additionally, they observed a training effect for all 1-RM tests (seated press, 26.6%; bench press, 28.5%; arm curl, 63.7%; and leg press, 37.1%). Interestingly, those who trained with a variable resistance demonstrated an increase in ease of performing daily tasks over those who trained intensely three times per week. These findings suggest that training too intensely or too frequently may result in increased fatigue and consequently a reduced training adaptation in older women due to insufficient time to recover.

Low volume training (LV, one set per exercise) compared to high volume training (HV, 3 sets per exercise) performed twice a week for 13 weeks induced similar improvements in maximal dynamic strength for knee extensors and elbow flexion, muscular activation of the vastus medialis and the biceps brachii, and muscle thickness for the knee extensors and elbow flexors in elderly women.62 The authors suggest that during the initial months of training, elderly women can significantly increase upper- and lower-body strength by utilizing low volume training. However, after longer periods of training, larger muscle groups may require greater training volume to provide further strength gains.63,64

Allowing individuals to self-regulate their exercise intensity to a preferred intensity may lead to greater enjoyment and stronger compliance to an exercise program.65-67 Additionally, it has been suggested that a low-intensity resistance exercise protocol may be more effective for older adults by increasing adherence rates.68,69 Compared to a high intensity resistance exercise program, lower attrition rates were observed when training used lower intensities (70% vs. 80% 1-RM) and frequencies (2 vs. 3 days).70 However, Elsangedy and colleagues71 recently found that older women engaged in an RT program that allowed them to self-select their training load selected loads that were less than that recommended for improvements in muscle strength and endurance (42% 1-RM compared to 50%_70% 1-RM). While this intensity is suitable for very deconditioned individuals, it may not provide enough overload to the body to elicit changes in strength and functional capacity. Though limited data exists on the chronic effects of self-selected training load on muscular fitness and functional autonomy, a recent study by Storer et al.72 observed significant improvements LBM, upper body strength, peak leg power, and VO2max in middle-aged males using a personal trainer compared to self-training. Albeit using males, this study supports the idea that guidance from a personal trainer and the use of a progressive overload, in which intensity is gradually increased over time, may be optimal to maximize chronic positive effects.

Traditional strength training, including the use of weight machines, has been shown to induce positive changes in

<jo HA

strength and FFM in older adults. However, it becomes

imperative to provide alternative methods of resistance training to the traditional use of weight machines, which may

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Table 3

Recommendations for exercise based on current research.

Activity type Frequency

Duration

Intensity

Examples

Aerobic 2—3 days/week >30 min Moderate intensity (50%-60% HRmax; RPE 5-6) Walking, jogging, swimming, and dancing

Resistance 2—3 days/week 8—10 exercises; Moderate intensity; 10-15 reps, Calisthenics (bodyweight exercises - pushups,

1—3 sets each where the last 1 -2 reps are difficult to perform (RPE 5-6 for moderate, 7-8 for vigorous) squats etc.), Resistance band exercises, Circuit training, Free-weight or machine weight exercise. Large, multi-joint exercises.

Flexibility >2 days/week 10 min; 8—10 stretches Light-moderate intensity; hold each stretch for 10-30 s, 3-4 reps each set. Stretch to the point of slight discomfort. Sit-and-reach, shoulder stretch

Abbreviations: RPE = Ratings of perceived exertion, on a scale of 0-10 for level of physical exertion; rep = repetition.

be more convenient for certain populations, including older women. In a recent study by Colado et al.,75 the authors examined three forms of RT (traditional weight machines (WM), elastic bands (EB), and aquatic devices(AD)) and compared their effectiveness at improving body composition and physical capacity. Following the 10-week training program, all three groups reduced FM (WM: 5.15%, EB: 1.93%, and AD: 2.57%), increased FFM (WM: 2.52%, EB: 1.15%, AD: 0.51%), in addition to upper- and lower-body strength, with minimal differences between the different groups.

5. Flexibility

Flexibility training has been shown to improve muscle and connective tissue properties, reduce joint pain, and alter muscle recruitment patterns.76 Although results from previous studies examining changes in flexibility following an intervention have provided mixed results, more recent studies have demonstrated significant improvements in range of motion of various joints in older adults participating in regular exer-cise.77-79 While the research examining interventions for improving flexibility in an older population is limited, increases of 5%-25% have been shown following interventions using a combination of aerobic exercise, RT, and stretch-ing.80,81 The typical duration for each exercise session was 60 min, performed three days per week for 12 weeks to one year. Filho et al.82 examined the effects of 16 weeks of combination (aerobic, flexibility, and resistance) training on metabolic parameters and functional autonomy in elderly women. Twenty-one women (68.9 ± 6.8 years) participated in three weekly sessions of stretching, resistance exercise, and moderate intensity walking for 16 weeks. Significant improvements in metabolic parameters, including glucose, triglycerides, total cholesterol, high density lipoproteins, LDL, blood pressure, and BMI were seen following the intervention. More so, the addition of resistance and flexibility exercises appeared to enhance functional autonomy (the ability to perform activities of daily living). Supporting these findings, Bravo et al.80 found that flexibility, agility, strength, and endurance all significantly improved following 12 months of an exercise program, in which participants performed weight bearing exercises (walking and stepping), aerobic dancing, and flexibility exercises for 60 min three times a week. The exercise group was also able to maintain spinal BMD while

control groups saw significant reductions. Furthermore, in a study by Hopkins et al.,65 65 older women participated in a 12-week exercise program, consisting of low-impact aerobics, stretching, and progressive dance movements. Each session was 50 min long and was performed three times per week. The exercising group significantly improved cardiorespiratory endurance, strength, balance, flexibility, agility, and body fat.

The aforementioned findings primarily include "combination" training where interventions include aerobic and/or resistance training with flexibility training. Thus we can't deduce what effect flexibility training alone had. However, combination training has been shown to be just as beneficial to flexibility as flexibility training alone.83,84 Therefore, with the positive adaptations from resistance training and aerobic training, the addition of flexibility training to an exercise intervention is warranted, and may improve functional autonomy, range of motion, balance, and mobility in older women (Table 2).

6. Recommendation

While current American College of Sports Medicine (ACSM) guidelines recommend light- to moderate-intensity activities to optimize health, moderate- to high-intensity exercise may be necessary to elicit positive CV adaptations and reduce the risk for CV disease. Older adults should aim to get at least 30 min of moderate activity, or 20 min of more vigorous activity (>6 METS or 60%-<90%HRR), 3 days a week. It is recommended that programs include low-impact, large muscle, rhythmic forms of exercise, including swimming, walking, biking, and dancing. More so, women may benefit from participating in group-based fitness classes, such as step aerobics and dance classes. Social support and group cohesiveness received from group fitness classes may help to increase self-efficacy, leading to long term adherence as well as greater enjoyment and satisfaction from the exercise pro-gram.85-87 The addition of stretching exercises (light to moderate intensity, hold for 30 s each muscle group, 3-4 repetitions) to these programs can serve to increase flexibility and range of motion.

ACSM recommends that older adults perform RT at least 2, non-consecutive days per week, including 8-10 exercises involving all the major muscle groups at moderate intensity (selecting a weight that allows 10-15 repetitions of each

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exercise), with 2-3 min of rest between each set. Additionally, those who are very deconditioned could start RT with a "very light" to "light" intensity (40%-50% 1-RM) to improve strength, power, and balance.27 It is advised that women unfamiliar with resistance training consult a fitness professional prior to beginning a program. It is suggested that one must use progressive overload to stimulate muscular adaptations to resistance exercise. Typical recommendations for progression of RT is to first increase repetitions, followed by an increase in weight (0.5 kg for upper body, 1 kg for lower body) per week. For optimal results from a resistance program, the focus should be on full-body, compound movements (Bench press, squat, pull-ups, etc.). Furthermore, adherence to group-based resistance training programs tends to be higher among older women than home based programs.88,89 Additionally, Elsan-gendy and colleagues71 recently found that women who self-selected resistance exercise intensity fell below current ACSM guidelines. Consequently, the participation in a supervised or group-based resistance exercise program may improve women's adherence and health benefits stemming from a higher intensity attained. Finally, the authors propose circuit training, which incorporates both resistance training and aerobics, as an attractive alternative for weight training. One of the major benefits to circuit training is that it can illicit the same positive physiological responses as traditional resistance training, thus providing a time-efficient alternative to improve muscular strength and functional fitness.90

The ACSM recommendations for flexibility are to aim for greater than 2-3 days per week, ultimately aiming for daily training. Static stretching should be held 10-30 s at a point of mild discomfort, although stretches lasting 30-60 s may provide additional benefits. 2-4 repetitions per exercise are recommended, aiming for at least 60 s of stretching for each major muscle-tendon unit (Table 3).27

The recommendations we have provided are general. The frequency, intensity, type, and duration of exercise one is able to achieve and maintain will vary from person to person. Thus we suggest that an individualized approach be utilized. While some activity is better than none, individuals aiming to improve CV health, muscular strength and endurance, and functional mobility should strive to meet the minimum recommendations we have provided.

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