Exercise
and Injury Patterns in a Sample of Active
Middle-Aged
Adults
Eric
D. Zemper, Ph.D.
Exercise Research Associates of
Presented at the International Congress on Sports Medicine and
Human Performance, in
ABSTRACT
As a pilot study of activity and injury patterns in middle-aged adults, data were collected monthly for 6 months from 25 regularly exercising adults (19 male, 6 female) aged 43-70 years (mean 54.0 yr). Each subject completed a daily exercise log noting type, duration and intensity of exercise, and distance covered (if appropriate). Any injuries or illnesses causing restriction of normal activity were recorded on separate check-off forms. Reports were received each of the 6 months from all subjects. The subjects accumulated 3209 exercise sessions, totaling 2631 hrs. The predominant activities were running (2128 sessions; 1780 hrs; 19,638 km), weightlifting (357 sessions; 181 hrs), walking (228 sessions; 195 hrs; 1064 km) and cycling (109 sessions; 78 hrs; 1992 km). All other exercise activities (e.g., tennis, swimming, rowing, water running) totaled 388 sessions and 397 hrs. The subjects averaged 4.0 hrs/week of exercise in 4.9 sessions/week of 49 min/session. Two-thirds of the sessions involved running, and 21 subjects ran regularly. These subjects ran an average of 3.9 times/week, 50.2 min/session, 38.2 km/week, 9.3 km/session at 5:24/km pace. While running was the predominant activity in this sample, each subject participated regularly in an average of 2.2 different exercise activities, and participated at least once in an average of 3.4 different activities during the period of this study. There were 30 time-loss injuries attributed to exercise in this sample, 23 involving the lower extremities. One-third of the total injuries involved the knee. There were 9.3 injuries/1,000 exercise sessions or 11.4 injuries/1,000 hrs of exercise. Each injury lasted an average of 10.7 days before return to unrestricted activity. However, many injuries resulted in modification of activity (e.g., decreased frequency, distance, pace, or doing alternative activities) rather than complete restriction of exercise. During this period there were 10 injuries recorded that did not involve exercise, 5 being lower back strains, with an average time-loss of 17.2 days. There also were 17 illnesses reported, primarily colds and flu, with an average time-loss of 7.4 days. Based on the results from this small pilot study, a middle-aged exerciser can expect 2.4 exercise-related injuries per year with a total of 25.8 days of modified or restricted activity, 0.8 non-exercise injuries per year with 13.8 days of restricted activity, and 1.4 illnesses affecting 10.4 days. On the average, this middle-aged exerciser can expect 4.6 injury or illness episodes affecting 50 days each year.
INTRODUCTION
It has become increasingly evident over the past 25 years that there is a need for data on injury rates for the variety of sports and physical activities in which people of all ages are becoming involved. The research literature on the epidemiology of sports-related injuries has been growing slowly as various individuals and groups have attempted to gather data on the risks of participating in various sports. Almost all of these attempts have focused on sports in an organized setting, for younger age groups, and have involved relatively short-term observations. With the recent increase in participation in general fitness activities, and with such participation being encouraged by the medical community as a public health intervention to promote healthy lifestyles, it often is not realized there is little or no dependable data available to assess the risks involved in participation in physical activities. Much effort is being expended in defining the benefits of exercise, but little is being done to define risk levels. Such information is needed in order to make informed decisions as to the value of participating in a particular activity, and to provide clues as to how injury rates can be reduced.
This paper presents some of the preliminary results on exercise patterns and injury rates for a six month study of a small sample of regularly exercising subjects. This pilot study was undertaken to test data collection forms and procedures for a planned longitudinal, prospective study of exercise and injury patterns in a large sample of middle-aged and older adults.
METHODS
Twenty-five volunteer subjects were obtained from the local community (
Subjects were instructed to record on a Daily Exercise Log each exercise session of any type that increased the heart rate for a minimum of 15 minutes. These forms collected data on the type, duration and intensity of exercise, and distance covered (if appropriate to the type of exercise). This provided exposure data or denominator data for calculating injury rates. The subjects also recorded on an Injury/Illness Report Form any injury or illness that: a) required formal or informal medical attention, and/or b) resulted in modification or restriction of normal activities for the remainder of that day or one or more days beyond the date of onset. These check-off forms collected data regarding the site, nature, circumstances and severity of the injury. The forms were returned at the end of each month using the stamped, self-addressed envelopes provided. Upon receipt in the project office, the forms were logged in and screened for completeness and logical consistency. Subjects were contacted regarding missing forms or data, or any questionable entries on the forms. After screening, the data from the forms were entered into computer files for storage and later analysis using locally developed software. Subjects completed and returned these forms for a six month period (1 January 1990 - 30 June 1990).
RESULTS
Forms were received from all 25 subjects for each of the six months of this pilot study. The subjects accumulated 3,209 exercise sessions totaling 2,631 hours, averaging nearly 5 sessions per week of about 50 minutes per session. Table 1 summarizes the amount of exercise activity in this sample, and provides a breakdown by gender and age group. In this particular sample, running/jogging comprised two-thirds of the exercise sessions (Table 2). Twenty-one of the subjects ran regularly, averaging nearly 4 sessions per week, 50 minutes per session, and 9.3 km per session at a pace of 5:24/km. Table 2 summarizes the exposure data for the three predominant activities (running, walking and weightlifting), and the cumulative totals for the other exercise activities, which included swimming, cycling, tennis, aerobics, rowing, stair climbing, water running, basketball, and various field events (long jump, pole vault, shot put, etc.). Although a majority of the subjects were from a local masters track club, each subject participated regularly in an average of 2.2 different exercise activities, and participated at least once during the period of this study in an average of 3.4 different exercise activities.
_______________________________________________________________________________________
Table 1. Total Exercise Activity by Gender
and Age Group
_______________________________________________________________________________________
|
|
__N__ |
# Exercise __sessions__ |
# Hours |
Average # Sessions/Week |
Average # Min./Session |
|
Total |
25 |
3,209 |
2,631 |
4.9 |
49.2 |
|
Male |
19 |
2,523 |
2,080 |
5.1 |
49.5 |
|
Female |
6 |
686 |
551 |
4.4 |
48.2 |
|
Male - 45-54 yrs |
12 |
1,447 |
1,180 |
4.6 |
48.9 |
|
Male - 55-64 yrs |
3 |
593 |
424 |
7.6 |
42.9 |
|
Male - 65+ yrs |
4 |
483 |
476 |
4.6 |
59.2 |
|
Female - 45-54 yrs |
5 |
546 |
431 |
4.2 |
47.4 |
|
Female - 65+ yrs |
1 |
140 |
120 |
5.4 |
51.3 |
_______________________________________________________________________________________
_______________________________________________________________________________________
Table 2. Total Exercise Activity by Type
and Gender
_______________________________________________________________________________________
|
|
_N_ |
# Exercise Sessions |
# Hours |
Average # Sessions/Wk |
Average # Min/Session |
_# Km_ |
Average # Km/Session |
|
Running |
|
|
|
|
|
|
|
|
Total |
21 |
2,128 |
1,780 |
3.9 |
50.2 |
19,638 |
9.3 |
|
Male |
17 |
1,802 |
1,539 |
4.1 |
51.2 |
17,219 |
9.6 |
|
Female |
4 |
326 |
241 |
3.1 |
44.4 |
2,419 |
7.4 |
|
Walking |
|
|
|
|
|
|
|
|
Total |
6 |
228 |
195 |
1.5 |
51.4 |
1,064 |
4.6 |
|
Male |
3 |
79 |
73 |
1.0 |
55.8 |
405 |
5.1 |
|
Female |
3 |
149 |
122 |
1.9 |
49.1 |
659 |
4.5 |
|
Weightlifting |
|
|
|
|
|
|
|
|
Total |
8 |
357 |
181 |
1.7 |
30.4 |
-- |
-- |
|
Male |
5 |
285 |
125 |
2.2 |
26.3 |
-- |
-- |
|
Female |
3 |
72 |
56 |
0.9 |
46.3 |
-- |
-- |
|
Other Sportsa |
|
|
|
|
|
|
|
|
Total |
22 |
496 |
475 |
0.8 |
57.5 |
-- |
-- |
|
Male |
13 |
357 |
343 |
1.1 |
57.6 |
-- |
-- |
|
Female |
9 |
139 |
132 |
0.6 |
57.0 |
-- |
-- |
_______________________________________________________________________________________
aOther sports
included: swimming, cycling, tennis aerobics, rowing machine, stair climbing,
water running, basketball and field events (long jump, pole vault, shot put,
etc.)
___________________________________________________________________________________________________
Table 3 summarizes the number of injuries and illnesses reported during the six months of this study. There were a total of 70 reports recorded, 18 being illnesses (primarily colds and flu), 15 injuries not related to exercise, and 37 exercise-related injuries. Seventeen of the 18 illnesses and ten of the 15 non-exercise injuries resulted in time-loss from normal exercise activities, and 30 of the 37 exercise-related injuries resulted in time-loss. Focusing on exercise-related time-loss injuries, Table 4 presents the injury rate by gender and age group. Three types of injury rates are presented: rate per 100 persons per year, which is the least precise type of injury rate (it cannot account for the sometimes large individual variations in amount of participation in exercise, or the amount of exposure to the possibility of being injured), and the more precise and useful rate per 1,000 athlete-exposures (A-E) (one A-E is one person taking part in one exercise session) and rate per 1,000 hours of exercise activity. Table 5 gives these rates by type of activity. In addition, a rate per 1,000 km for running and walking is presented in Table 5. Finally, Table 6 presents the average time-loss by gender for illnesses, non-exercise injuries and exercise-related injuries.
_______________________________________________________________________________________
Table 3. Distribution of
Injuries/Illnesses by Gender and Age Group
_______________________________________________________________________________________
|
|
|
|
____Non-Exercise____ |
___Exercise-Related___ |
|||
|
|
Total # Illnesses |
Total # Injuries |
Total # Injuries |
# Time-Loss __Injuries__ |
Total # Injuries |
# Time-Loss __Injuries__ |
|
|
Total |
18 |
52 |
15 |
10 |
37 |
30 |
|
|
Male |
13 |
42 |
10 |
6 |
32 |
25 |
|
|
Female |
5 |
10 |
5 |
4 |
5 |
5 |
|
|
Male - 45-54 yrs |
8 |
20 |
4 |
3 |
16 |
15 |
|
|
Male - 55-64 yrs |
3 |
12 |
3 |
1 |
9 |
4 |
|
|
Male - 65+ yrs |
2 |
10 |
3 |
2 |
7 |
6 |
|
|
Female - 45-54 yrs |
5 |
8 |
4 |
4 |
4 |
4 |
|
|
Female - 65+ yrs |
0 |
2 |
1 |
0 |
1 |
1 |
|
_______________________________________________________________________________________
_______________________________________________________________________________________
Table 4. Exercise-Related Time-Loss
Injury Rates by Gender and Age Group
_______________________________________________________________________________________
|
|
Per 100/Yr |
Per 1,000 A-Ea |
Per 1,000 Hrs |
|
Total |
240.0 |
9.3 |
11.4 |
|
Male |
263.2 |
9.9 |
12.0 |
|
Female |
166.7 |
7.3 |
9.1 |
|
Male - 45-54 yrs |
250.0 |
10.4 |
12.7 |
|
Male - 55-64 yrs |
266.7 |
6.7 |
9.4 |
|
Male - 65+ yrs |
300.0 |
12.4 |
12.6 |
|
Female - 45-54 yrs |
160.0 |
7.3 |
9.3 |
|
Female - 65+ yrs |
200.0 |
7.1 |
8.4 |
_______________________________________________________________________________________
aA-E = Athlete-Exposure; one subject taking part in one
exercise session where he or she is exposed to the possibility of being
injured.
____________________________________________________________________________________________________
____________________________________________________________________________________________________
Table 5. Time-Loss Injury Rates by
Activity and Gender
_______________________________________________________________________________________
|
|
Per 100/Yr |
Per 1,000 A-Ea |
Per 1,000 Hrs |
Per 1,000 Km |
|
Running |
|
|
|
|
|
Total |
228.6 |
11.3 |
13.5 |
1.3 |
|
Male |
235.3 |
11.1 |
13.0 |
1.2 |
|
Female |
200.0 |
12.3 |
16.6 |
1.6 |
|
Walking |
|
|
|
|
|
Total |
33.3 |
4.4 |
5.1 |
0.9 |
|
Male |
66.7 |
12.7 |
13.6 |
2.5 |
|
Female |
0.0 |
0.0 |
0.0 |
0.0 |
|
Weightlifting |
|
|
|
|
|
Total |
50.0 |
5.6 |
11.1 |
-- |
|
Male |
80.0 |
7.0 |
16.0 |
-- |
|
Female |
0.0 |
0.0 |
0.0 |
-- |
|
Other Sports |
|
|
|
|
|
Total |
150.0 |
14.0 |
11.6 |
-- |
|
Male |
133.3 |
14.9 |
12.7 |
-- |
|
Female |
200.0 |
12.5 |
10.0 |
-- |
____________________________________________________________________________________________________
aA-E = Athlete-Exposure; one subject taking part in one
exercise session where he or she is exposed to the possibility of being
injured.
____________________________________________________________________________________________________
____________________________________________________________________________________________________
Table 6. Average Time-Loss per
Injury/Illness
_______________________________________________________________________________________
|
|
Average # Days per _____Illness_____ |
Average # Days per Non-Exercise Injury |
Average # Days per __Exercise Injury__ |
|
Total |
7.4 |
17.2 |
10.7 |
|
Male |
7.3 |
10.5 |
8.6 |
|
Female |
7.8 |
27.3 |
21.4 |
_______________________________________________________________________________________
DISCUSSION
There were 30 time-loss injuries attributed to exercise in this sample. Twenty-three of these injuries were to the lower extremities; ten of these injuries involved the knee. This is not unexpected, since two-thirds of the recorded activity sessions involved running, and a number of the other types of recorded activities also involved major stress on the feet and legs (e.g., aerobics, tennis, basketball). As we get older, it is generally believed that we are more susceptible to low back injuries. It is interesting to note that 3 of the 30 exercise-related time-loss injuries were lower back strains, while 5 of the 10 non-exercise injuries were lower back strains. Each illness lasted an average of about 1 week, and was nearly the same for men and women. The average period of a non-exercise injury was 17 days, while for an exercise-related injury it was nearly 11 days. The higher average length of time-loss for exercise and non-exercise injuries for women should not be considered significant in this case, because of the small sample size for women, the small number of injuries they recorded, and the fact that a couple of the injuries involved particularly lengthy recovery times. The average time-loss of 10.7 days before return to unrestricted activity for exercise injuries may also be somewhat deceptive, because a majority of the injuries did not result in complete cessation of physical activities during the recovery period, but rather a modification of activity (e.g., decreased frequency of exercise, decreased distance covered, slower pace, or doing alternative exercise activities not involving the injured body part).
This small sample averaged 9.3 injuries per 1,000 exercise sessions, or 11.4 injuries per 1,000 hours of exercise activity. Stated in an alternative manner, these exercisers could expect an injury once in every 110 exercise sessions or once in every 90 hours of exercise activity. For the men, for whom the greatest amount of data was collected, it is interesting to note in Table 5 that the injury rate per 1,000 hours of activity is essentially the same across all the exercise categories. Based on the results from this pilot study, a middle-aged exerciser can expect 2.4 exercise-related injuries per year with a total of 25.8 days of modified or restricted exercise activity, 0.8 non-exercise injuries per year with 13.8 days of restricted activity, and 1.4 illnesses affecting 10.4 days. On the average, this middle-aged exerciser can expect a total of 4.6 injury or illness episodes affecting 50 days each year. Exercise activity will not necessarily be prevented on all of these days, but it may have to be modified in some way. It should be noted that these injury rates for older exercisers should not be directly compared to data obtained from other groups such as high school and college athletes. Compared to school and collegiate athletes, who tend to “play through” minor injuries that therefore would not be recorded as time-loss injuries, older exercisers feel no such pressure to ignore minor injuries and are much more willing to take time off for these relatively minor injuries. Thus, the time-loss injury rate for older exercisers could be considered to be “artificially inflated” compared to those seen for younger athletes.
Although these data present an interesting glimpse of activity and injury patterns in a group of active middle-aged adults, this pilot study involved a relatively small number of subjects and covered a period of only six months. However, it was successful in demonstrating the utility of the data collection forms and the feasibility of doing a prospective epidemiologic study of this design of exercise and injury patterns in middle-aged adults. This type of data from a habitually active population of middle-aged adults will be necessary in order to better define some of the risks inherent in various types, frequencies and intensities of activity. Such information should be provided to individuals who are being urged to adopt a more active lifestyle, in order that they may make better informed decisions about the best types of exercise activity to fit their particular situations.
____________________
(The following are two additional tables dealing with injury distribution in adult runners that were not part of the original presentation.)
_______________________________________________________________________________________
A Percent Comparison of Injuries by Type in Older Recreational Runners*
_______________________________________________________________________________________
|
Injury Type |
_N_ |
_%_ |
|
Bursitis |
2 |
6.5 |
|
Cartilage - Torn |
1 |
3.2 |
|
Contusion |
2 |
6.5 |
|
Inflammation |
3 |
9.7 |
|
Laceration |
1 |
3.2 |
|
Sprain (ligament) |
4 |
12.9 |
|
Strain (muscle) |
13 |
41.9 |
|
Tendonitis |
__5__ |
_16.1_ |
|
Totals |
31 |
100.0 |
_______________________________________________________________________________________
* 21 runners (>45 yrs old; 17 male, 4 female); 6 months; 2,128 sessions; 1,780 hrs; 19,638 km (avg. 9.3 km/session). Any injury types not listed were not reported.
_______________________________________________________________________________________
_______________________________________________________________________________________
A Percent Comparison of Injury Location in Older Recreational Runners*
_______________________________________________________________________________________
|
Body Part |
_N_ |
_%_ |
|
Head |
1 |
3.2 |
|
Lower Back |
2 |
6.5 |
|
Pelvis, Hips |
2 |
6.5 |
|
Buttocks |
1 |
3.2 |
|
Upper Leg (quads) |
2 |
6.5 |
|
Hamstring |
3 |
9.7 |
|
Knee |
9 |
29.0 |
|
Lower Leg |
5 |
16.1 |
|
Ankle |
3 |
9.7 |
|
Heel/Achilles Tendon |
__3__ |
_9.7_ |
|
Totals |
31 |
100.1 |
_______________________________________________________________________________________
* Note: Any body parts not listed here were not reported as injured.
_______________________________________________________________________________________