The Relationship between Age and Change in Physical Functions after Exercise Intervention. Trainability of Japanese Community-Dwelling Older Elderly

Abstract

The purposes of this study were to evaluate the relationship between age and changes in physical measurements after exercise intervention and to investigate the trainability of the older elderly. Two hundred seventy-six community-dwelling people aged 60 years and older practiced exercise intervention for 3 months. The measurements of physical functions were one-legged standing with eyes open and closed (OLS-O, OLS-C), functional reach test (FR), timed up and go test (TUG), maximum walking velocity, flexibility, and muscle strength. We evaluated the associations between age and the changes in these physical measurements. All measurements except for OLS-C significantly improved after intervention. The magnitude of the changes in hand-grip strength and FR after the intervention showed weak negative correlations with the subject's age, but other measurements showed no correlations. In addition, there were no differences between younger elderly persons and older elderly persons with regard to changes in any measurements. These results suggested that the exercise intervention we applied could improve physical fitness in community-dwelling older people, regardless of their age. The older elderly were comparable to the younger elderly in trainability to improve physical fitness.

Preventing falls and reducing the risks of falling among older people are public health issues in many countries^1–3). It has been suggested that an exercise intervention program that includes strengthening of the lower extremities and functional training such as balance training could improve physical function and reduce risks of falling in older adults^4–8). Although the effectiveness of strength training for the older elderly has been well established^9,10), if we want to employ exercise intervention as a preventive strategy, we must consider the fact that there are many older people in a given community, with different physical conditions. Ways to maximize the effectiveness of exercise intervention should be determined, because researchers have suggested that some interventions that targeted subjects who were at too high or too low a risk of falling failed to be effective^3,11). Therefore, it is necessary to determine what kind of exercise is effective for persons in various age-groups. Moreover, we need information about whether trainability of the older elderly declines in comparison with that of the younger elderly. However, to our knowledge, no such information has been reported. This information would be indispensable for implementing an effective preventive strategy. We feel that this information can be best obtained from an intervention conducted not at the laboratory level but in a real-life setting.

The purposes of this study were to evaluate the relationship between age and changes in physical measurements after exercise intervention and to investigate the trainability of the older elderly.

Subjects and Methods

Participants

The participants were 276 community-dwelling older people. The number of subjects in each age group is shown in Table 1. We defined that the subjects 75 years old or older were older elderly, then 119 (43.1%) were divided into the younger elderly group and 157 (56.9%) were divided into the older elderly group. They were residents of the seven cities that comprise the Tokyo metropolitan area and were recruited through advertisements published in various community publications and through the encouragement of the public health nurses in the area. The inclusion criteria were: the participants had to be community-dwelling, aged 60 years or older, and not meet any of the exclusion criteria. The exclusion criteria are described below. Because the inclusion criteria were announced in the community publications and were made known to all public health nurses who encouraged older people to participate, all of the 276 participants met the eligibility criteria. Although we did not examine the participants' cognitive function, a medical doctor examined their current medical history and, by using a simple interview, he confirmed that the subjects did not suffer from dementia or depression. This study was performed under the approval and the management of each local government of these seven cities. The intervention was described in detail to the subjects before the intervention began, and written informed consent to participate was obtained.

Table 1. Number of Subjects.

Age	Total	Male	Female
60–64	10	4	6
65–69	42	17	25
70–74	67	26	41
75–79	84	31	53
80–84	51	20	31
85–89	18	1	17
90–94	1	1	0
95–99	3	1	2
Total	276	101	175

The exclusion criteria for the exercise intervention were: 1. Cerebrovascular or cardiovascular accidents reported within the past 6 months; 2. Acute liver problems or active chronic hepatitis; 3. Diabetic mellitus with a history of hypoglycemic attack, or with fasting levels of plasma glucose concentrations of 200 mg/dl or higher, or with complications such as retinopathy or nephropathy; 4. Systolic blood pressure above 180 mmHg or diastolic blood pressure above 110 mmHg at rest; and 5. Diagnosis of heart disease, an acute orthopedic problem, or dementia made by a medical doctor and recommendation by this doctor that the subject be excluded. Even if the participants did not meet these exclusion criteria, we confirmed that their physical activities were not restricted by a medical doctor.

Basic investigation of the subjects

We used interviews and questionnaires to evaluate the participants regarding their medical history before the intervention began. A physical evaluation involving age, height, body weight, and body mass index (BMI) was performed pre-intervention and post-intervention.

Measurements of physical function

The physical functions necessary to perform daily activities were evaluated. The measurements were maximum walking velocity (MWV)¹²⁾, sit and reach test (SR) used as a test of flexibility of the hamstrings¹³⁾, handgrip strength (HS)^14,15), and isometric knee extensor strength (KS)^16–18). In the MWV test, subjects were asked to walk a track that was 11 m long. This track included a measured section of 5 m with an extra 3 m section at each end. The examiner recorded the time that the subject took to walk along the middle 5 m of the track with a stopwatch. KS was measured while subjects were sitting on a treatment table with their knees and hips at 90 degrees of flexion. We used a hand-held dynamometer to test knee extensor strength. The dominant leg was measured. The subject determined the stronger leg to be the dominant leg. One-legged standing with eyes open (OLS-O) and closed (OLS-C) were used to measure static balance^19,20). The functional reach test (FR) was used to measure dynamic balance^21,22). The timed up and go test (TUG) was used to measure functional balance²³⁾. We slightly modified the methodology of this test because we thought that it is necessary to rush the subjects to determine their maximal abilities. The instructions to the subjects were modified as follows: “Please return to the chair as quickly as you can without falling.” We chose these measurements because of their reliability and convenience, and because they have frequently been used in research studies to report the relationship of balance function to the occurrence of falls²⁴⁾. The subjects performed these tests twice, and the measurement recorded was the maximum value of the two results. These assessments were performed by trained physical therapists and nurses.

Protocol of exercise intervention

Exercise intervention was conducted at a public gymnastic hall in each of the seven communities. We used a training protocol called “Comprehensive Geriatric Training” that included high-intensity resistance training and balance training. This exercise program was constructed according to the American College of Sports Medicine guidelines, 1998²⁵⁾, and other related research^26–28). The exercise training and management were conducted by an interdisciplinary team consisting of medical and fitness staff. The medical staff performed medical management, and they developed appropriate emergency response plans and trained their staff in executing these plans.

The characteristics of this program were as follows: 1. The physical functions focused on in this program were muscular strength of the lower extremities, balance functions, flexibility, and daily functions such as climbing stairs; 2. Physical therapists managed the program of participants who had pain; 3. The program was a group program in which instruction was given to fewer than 10 subjects at a time; 4. The duration of the program was 3 months, with classes conducted for 1.5 hours, twice a week; and 5. The program was divided into three periods: the “Conditioning Period,” the “Muscular Strength Enhancement Period,” and the “Functional Training Period”. The target and intensity of training was individually set in each period.

Every session began with a 10- to 15-minute warm-up consisting of gentle stretching and light exercise and ended with a 10-minute cool-down consisting of stretching. During the Conditioning Period, we focused primarily on physical conditioning. The subjects spent a great deal of time doing exercises that stretched their muscles. The subjects were also familiarized with weight training machines and the technique of training at low intensity with frequent repetitions. At the beginning of the Muscular Strength Enhancement Period, the subject's one repetition maximum (1RM) was measured directly. The 1RM test was conducted by the subjects who could lift the weights of a training machine in an adequate manner. The subjects were trained using four weight training machines (Leg press machine, Leg extension machine, Hip abduction machine, and Rowing machine) at 60% or more of their 1RM for 2 or 3 sets of 10 repetitions. The subjects who could not lift the weights in an adequate manner continued training with fewer sets, lower loads, and frequent repetitions. If the subjects were able to effortlessly complete 2 sets of 10 repetitions, we first increased the sets of training from two to three, and then we increased the weight on the training machine. If there were participants with specific physical problems, such as pain or joint immobilization, physical therapists treated their problems individually by controlling the load and range of motion and also tried to avoid pain in the subjects by trying other possible techniques. Subjects also underwent balance training in this period. During the Functional Training Period, in addition to the high-intensity resistance training described above, the program included intensive balance training and functional training exercises. The tasks of balance and functional training progressively increased in difficulty based on set criteria and dependent on the individual's ability. Functional training that required more dynamic and rapid movement of the center of gravity was also introduced. For example, the target of the training in the early phase of the training period was to stand stably against small perturbations with a narrow base of support. During the first phase of the training period, correct trunk and lower-body alignment in the standing position with wide lower extremity stances was emphasized. The base of support was gradually reduced as their lower extremity stances narrowed. The subjects who could not stand stably with correct alignment were allowed to use simple stabilizing equipment such as a chair or parallel bars. Then, if we wanted to increase the difficulty of the static balance training, subjects were asked to stand on one foot or to raise their heels or toes while standing without stabilizing equipment. We did not use specialized devices to create perturbations. The small perturbations that were used in this study were introduced by subjects actively raising their arms, twisting their trunks, catching or throwing an object, being pushed by the therapist, etc. Additionally, a foam surface that makes it difficult to control the sway of the subject's body mass was introduced to the base of support. In the next phase, the subjects tried to widely move their centers of gravity rapidly on their bases of support with coordinated movements of the lower extremities and trunk. In the final phase, the subjects performed high-level functional tasks such as braiding while walking sideways, walking with bended knees, jumping and landing on the floor, etc.

Statistical analyses

A paired-t test was used to examine the differences in physical functions between pre- and post-investigation. The magnitude of the changes in the measurement after exercise intervention was calculated as the post-investigation value minus the pre-investigation value. To make it easy to evaluate the data, a negative change value which indicated improvement in the TUG test was changed to a positive value. We used the Pearson's correlation coefficient to evaluate the relationship between the magnitude of the changes in the measurements and subject's age. An unpaired-t test was used to examine the differences in the changes of physical functions between younger elderly and older elderly.

We used the SPSS 15.0J for Windows statistical software (SPSS Inc., Chicago, IL USA). P values less than 0.05 were considered statistically significant.

Results

Twenty-two subjects were not able to complete the intervention, either because of a loss of interest or because of an accident not directly related to the intervention. The reasons for dropping out also included hospitalization and illnesses such as colds. No severe adverse event was reported during the intervention period.

The evaluations of measurements for all subjects are shown in Table 2. All physical measurements, except for OLS-C, improved significantly after the intervention (p< 0.01) (Table 2). Significant differences in many measurements were found in the comparison of the two age groups before and after the intervention (Table 3 and Table 4). In addition, significant correlations between the subject's age and physical measurements were observed before and after intervention (Table 5). However, there were no differences between the younger elderly and older elderly with regard to changes in any of the measurements (Table 6). The magnitude of the changes in hand-grip strength (r = –0.131, p< 0.05) and FR (r = –0.183, p< 0.01) were negatively correlated with age, but other measurements revealed no significant correlation with age (Table 7).

Table 2. Evaluations of Measurements for All Subjects.

Physical Measurements (unit)	n	Pre-Exercise	Post-Exercise	p-value
		Mean ± SD	Mean ± SD
Age	276	75.3 ± 6.5	−	−
Height (cm)	247	153.4 ± 9.2	−	−
Weight (kg)	276	54.7 ± 10.2	−	−
BMI	247	23.1 ± 3.4	−	−
TMIG-Index(/13)	228	11.4 ± 2.3	−	−
Maximum walking velocity (m/min)	245	86.4 ± 30.1	97.5 ± 32.8	.000
Hand-grip strength (kg)	254	23.1 ± 7.0	24.3 ± 7.0	.000
Functional reach test (cm)	254	29.2 ± 6.8	31.8 ± 6.7	.000
Sit and reach test (cm)	250	29.1 ± 10.8	32.4 ± 9.8	.000
One-legged standing with eyes open (sec)	245	26.4 ± 22.6	29.9 ± 22.5	.000
One-legged standing with eyes closed (sec)	229	4.3 ± 4.4	4.7 ± 4.2	.153
Timed Up and Go test (sec)	242	8.5 ± 4.3	7.3 ± 3.6	.000
Knee extensor strength (N)	252	234.6 ± 94.9	262.0 ± 103.8	.000

SD: Standard Deviation

Table 3. Differences in Measurements between Younger Elderly and Older Elderly, Male and Female before Intervention.

	Difference in Age group					Difference in Gender
	Younger elderly		Older elderly			Male		Female
Physical Measurements (unit)	n	Mean ± SD	n	Mean ± SD	p-value	n	Mean ± SD	n	Mean ± SD	p-value
Age	119	69.5 ± 3.4	157	80.1 ± 4.3	0.000	101	74.8 ± 6.2	175	75.9 ± 6.7	0.162
Height (cm)	103	154.9 ± 8.8	143	152.3 ± 9.3	0.026	85	162.4 ± 7.2	161	148.6 ± 6.0	0.000
Weight (kg)	119	56.5 ± 9.9	156	53.4 ± 10.3	0.012	101	61.1 ± 8.6	174	51.0 ± 9.1	0.000
BMI	103	23.4 ± 3.3	143	22.9 ± 3.5	0.278	85	23.2 ± 2.7	161	23.1 ± 3.8	0.779
TMIG-Index(/13)	100	11.5 ± 2.4	128	11.4 ± 2.2	0.758	88	11.1 ± 2.4	140	11.6 ± 2.2	0.067
Maximum walking velocity (m/min)	112	89.7 ± 34.5	150	82.8 ± 27.3	0.082	95	85.3 ± 34.0	161	86.0 ± 28.7	0.863
Hand-grip strength (kg)	118	24.8 ± 7.2	152	21.4 ± 6.4	0.000	100	28.5 ± 6.9	170	19.5 ± 4.4	0.000
Functional reach test (cm)	118	31.2 ± 6.3	153	27.5 ± 7.0	0.000	99	30.4 ± 7.2	171	28.3 ± 6.7	0.016
Sit and reach test (cm)	116	31.1 ± 10.5	149	27.3 ± 10.7	0.005	97	23.6 ± 10.3	168	32.1 ± 9.8	0.000
One-legged standing with eyes open (sec)	116	31.8 ± 22.7	146	21.4 ± 21.4	0.000	95	26.2 ± 22.8	167	25.8 ± 22.5	0.901
One-legged standing with eyes closed (sec)	114	5.3 ± 6.9	138	3.6 ± 3.8	0.022	90	3.9 ± 4.0	162	4.6 ± 6.1	0.333
Timed Up and Go test (sec)	109	8.1 ± 4.8	150	9.2 ± 4.4	0.056	92	8.7 ± 4.9	167	8.7 ± 4.5	0.982
Knee extensor strength (N)	118	257.9 ± 103.4	150	213.7 ± 81.2	0.000	100	289.0 ± 99.7	168	200.3 ± 72.5	0.000

SD: Standard Deviation

Table 4. Differences in Measurements between Younger Elderly and Older Elderly, Male and Female after Intervention.

	Difference in Age group					Difference in Gender
	Younger elderly		Older elderly			Male		Female
Physical Measurements (unit)	n	Mean ± SD	n	Mean ± SD	p-value	n	Mean ± SD	n	Mean ± SD	p-value
Maximum walking velocity (m/min)	107	100.0 ± 38.4	138	95.6 ± 27.7	0.315	91	96.1 ± 38.8	154	98.3 ± 28.8	.632
Hand-grip strength (kg)	113	26.5 ± 7.3	142	22.4 ± 6.4	0.000	96	29.9 ± 7.0	159	20.7 ± 4.4	.000
Functional reach test (cm)	113	34.2 ± 5.9	142	29.9 ± 6.6	0.000	96	33.1 ± 6.7	159	31.1 ± 6.6	.018
Sit and reach test (cm)	111	35.3 ± 9.4	139	30.1 ± 9.6	0.000	93	28.6 ± 9.8	157	34.7 ± 9.1	.000
One-legged standing with eyes open (sec)	112	33.8 ± 22.5	137	25.9 ± 22.1	0.006	91	29.3 ± 22.5	158	29.6 ± 22.7	.919
One-legged standing with eyes closed (sec)	104	5.0 ± 4.2	134	4.3 ± 4.1	0.160	86	4.9 ± 4.5	152	4.4 ± 3.9	.362
Timed Up and Go test (sec)	112	7.0 ± 3.7	139	7.6 ± 3.5	0.175	94	7.6 ± 4.3	157	7.1 ± 3.1	.345
Knee extensor strength (N)	113	295.1 ± 114.9	142	233.2 ± 86.3	0.000	96	322.2 ± 116.1	159	223.5 ± 75.7	.000

SD: Standard Deviation

Table 5. Pearson's Correlation Coefficients for Subject's Age and Physical Measurements.

	Before			After
Physical Measurements (unit)	n	r	p-value	n	r	p-value
Height (cm)	247	−.177	.005	−	−	−
Weight (kg)	276	−.216	.000	−	−	−
BMI	247	−.123	.055	−	−	−
TMIG-Index(/13)	228	−.106	.112	−	−	−
Maximum walking velocity (m/min)	245	−.168	.006	245	−.135	.035
Hand-grip strength (kg)	254	−.303	.000	255	−.357	.000
Functional reach test (cm)	254	−.235	.000	255	−.369	.000
Sit and reach test (cm)	250	−.151	.014	250	−.200	.001
One-legged standing with eyes open (sec)	245	−.317	.000	249	−.292	.000
One-legged standing with eyes closed (sec)	229	−.180	.004	238	−.148	.022
Timed Up and Go test (sec)	242	.226	.000	251	.203	.001
Knee extensor strength (N)	252	−.289	.000	255	−.343	.000

r: Correlation Coefficient

Table 6. Differences between Younger Elderly and Older Elderly in Magnitude and Rate of Change.

	Magnitude of Change					Rate of Change (%)
	Younger Elderly		Older Elderly			Younger Elderly		Older Elderly
Physical Measurements (unit)	n	Mean ± SD	n	Mean ± SD	p-value	n	Mean ± SD	n	Mean ± SD	p-value
Maximum walking velocity (m/min)	107	11.7± 17.7	138	10.6± 14.5	0.602	107	15.9± 24.4	138	14.9± 20.7	0.739
Hand-grip strength (kg)	113	1.5± 3.2	141	0.9± 2.6	0.106	113	8.0± 18.1	141	5.9± 14.3	0.296
Functional reach test (cm)	113	3.1± 5.5	141	2.2± 5.6	0.198	113	12.5± 21.2	141	11.4± 26.5	0.735
Sit and reach test (cm)	111	4.1± 6.8	139	2.7± 8.2	0.130	111	20.4± 35.0	139	21.5± 50.9	0.843
One-legged standing with eyes open (sec)	111	2.3± 15.5	134	4.5± 13.3	0.241	111	68.4 ± 294.5	134	84.5± 184.6	0.604
Timed Up and Go test (sec)	104	1.2± 1.9	138	1.1± 2.2	0.944	104	11.1± 14.6	138	11.7± 16.2	0.755
Knee extensor strength (N)	113	36.5± 89.4	139	20.1± 61.0	0.099	113	24.1± 53.6	139	15.9± 35.8	0.149

SD: Standard Deviation

Table 7. Pearson's Correlation Coefficients for Subject's Age and Magnitude and Rate of Change.

	Magnitude of Change			Rate of Change
Physical Measurements(unit)	n	r	p-value	n	r	p-value
Maximum walking velocity (m/min)	245	–.023	.723	245	.033	.612
Hand-grip strength (kg)	254	–.131	.037	254	–.111	.076
Functional reach test (cm)	254	–.183	.003	254	.–091	.149
Sit and reach test (cm)	250	–.044	.485	250	.010	.877
One-legged standing with eyes open (sec)	245	.048	.451	245	–.007	.909
Timed Up and Go test (sec)	242	. 062	.339	242	.062	.340
Knee extensor strength (N)	252	–.097	.124	252	.056	.373

r: Correlation coefficient

Discussion

The purposes of this study were to evaluate the relationship between age and changes in physical measurements after exercise intervention and to investigate the trainability of the older elderly.

Except for the one-legged standing with eyes closed, most physical functions of the older people improved significantly with the exercise intervention, which combined strength and balance training. The results of this research did not contradict those of past studies which demonstrated improvements in physical function in response to exercise intervention^4–6,8). A number of studies have revealed that the physical function of older adults in general declines over time^6,19,29,30). Although there were no control subjects in this study, which was a limitation of this study, the fact that physical measurements improved may be due to the effects of the exercise intervention. In this research, OLS-C was not improved by strength training, probably because it is more challenging for older people to control the sway of their body mass without visual information³¹⁾. Without visual information, more effort is required by the neuromuscular system to achieve postural control, because sensory input is limited to only the vestibular and somatosensory (proprioceptive) systems. If we want to improve the OLS-C of older adults, more specific training such as dynamic balance training while blindfolded should be included.

Generally, it has been thought that the trainability of elderly people declines with age, but this image was not based on clear evidence. Indeed, there were relationships between a subject's age and some physical functions before and after the intervention. However, most of the changes in measurements, which were our main focus, did not show a relationship with the subjects' age, and there were no differences regarding changes in physical functions between younger elderly and older elderly. The relationships between the magnitude of the changes in hand-grip strength and FR during the intervention period and age were significant but very small. The results of our research suggest that the effects of exercise intervention, including strength and balance training, might not be affected by the subject's age. Furthermore, elderly people of all age groups could improve their fitness level by participating in an appropriate exercise program.

In past studies, the researchers concluded that intervention should be used in subjects in whom it was expected to have good effects. The results of the current research could provide more information that would be helpful in planning effective strategies for improving or maintaining the physical functions of community-dwelling elderly people. Thus, the authors believe that we should consider the subject's physical condition rather than the subject's age when prescribing exercise programs for older people. Consequently, further research is needed to examine how exercise intervention could be more effective and what kind of exercise would be useful to prevent the decline of physical functioning in community-dwelling elderly people. Further studies on the various kinds of problems that frequently afflict the frail elderly, including complications from illnesses, pain, depression, fear of falling, medications, nutrition, and the influence of lifestyle (i.e., sedentary or active), are warranted.