Abstract
Recovery from a hard running effort determines when a runner can run at an intense level again. Overtraining is often caused by insufficient recovery, which ultimately hurts endurance performance. The number of recovery hours needed to sufficiently restore the body back to peak racing condition is unknown. The purpose of this study was to compare 5km running performance after 24 hours and 72 hours of recovery. Twelve well-trained runners (9 males and 3 females) completed two successive 5km performance trials on two separate occasions. Immediately following the baseline 5km trial, runners recovered passively for 24 hrs (R24) and 72 hrs of passive recovery (R72), and then performed a second 5km trial. The 5km time trial sessions were separated by 6-7 days of normal training and performed in a counterbalanced order. R24 (19:59 + 1.9 min) was significantly (p = 0.03) slower than baseline (19:49 + 1.9 min). However, no significant differences (p = 0.21) were found between R72 (19:30 + 1.5 min) and baseline (19:34 + 1.6 min). HRave for R24 (177.3 + 6.3 b/min) was the same as baseline (177.3 + 7.3 b/min), yet R72 HRave (177.9 + 6.3 b/min) was significantly higher (p = 0.04) than baseline (175.4 + 6.5 b/min). RPEend for R24 (19.5 + 0.8) was not significantly different (p = 0.39) than baseline (19.6 + 0.8), but R72 RPEend (19.8 + 0.6) was significantly (p = 0.01) greater than baseline (19.3 + 0.9). For the R24 trials, 9 participants ran a mean 17.4 + 12.1 secs slower and 3 participants ran a mean of 13.3 + 6.8 secs faster than baseline. During R72, three individuals ran a mean 10.3 + 5.7 secs slower, five individuals ran a mean 17.4 + 12.9 secs faster, and four individuals ran within 3.3 + 1.8 secs of their first run. Results indicate that 72 hrs of passive recovery, on average, permits maintenance of successive 5km time trial performance, yet individual variability existed regarding rate of decline of 2nd trial performance. Future research is needed to determine if a longer or shorter recovery time will maintain or improve 5km racing performance.
Introduction
Coaches and runners constantly strive to identify legal methods to improve runners’ performances. Factors such as tempo runs, hill repeats, long-slow distance days, striders and build-ups, intervals and repeats, dietary intake, and sleep patterns, are continually tested and adjusted to produce better performance. However, one factor often overlooked is recovery. Many runners feel that to race faster, they should have longer daily runs, run more miles per week, or train faster and harder. This often leads to overtraining, which hurts performance. Recovery from hard running efforts plays a vital role in determining when a runner can run at an intense level again (Fitzgerald, 2007).
Previous studies have focused on recovery from long endurance races such as marathons and ultra-marathons (Gomez et al., 2002; Martin & Coe, 1997; Noakes, 2003). Recovery from these endurance efforts revolves around repairing of damaged muscle fibers and replenishing glycogen stores (Fitzgerald, 2007; Gomez et al., 2002; Nicholas et al., 1997). In shorter duration endurance activities, such as a 5km (3.1 miles), 10km (6.2 miles) race, or hard training runs, Foss and Keteyian (1998) indicate that muscle and liver glycogen levels may be normalized 24 hrs after exercise, but muscle function may not be fully recovered and performance measures may be sub-optimal.
Former University of Oregon track coach Bill Bowerman first popularized the concept of hard/easy training, indicating that intense workouts such as an interval session, tempo run, or long run, should be followed the next day by an easy run (Dellinger & Freeman, 1984). Using Bowerman’s method, a runner would have an intense workout every 48 hrs to allow muscle function to be restored to normal (O’Conner & Wilder, 2001). Also, New Zealander Jack Foster indicated a runner should take one recovery day for every mile completed in a race [Brown & Henderson, 2002; Galloway, 1984; Henderson, 2000; Higdon, 1998; Sinclair, Olgesby, & Piepenburg, 2003). However, Henderson indicated that it may be better to take one easy day per kilometer (Brown & Henderson, 2002; Henderson, 2000). Although, Bowerman, Henderson, & Foster’s statements about recovery days after a race or hard effort seem reasonable, the appropriate recovery duration as well as what is considered “easy” has not been previously studied.
Gomez et al. (2002) determined that strength and power capabilities of distance runners after a 10km race normalized after 48 hrs of passive recovery. Thus, it is likely that participants would be fully recovered, which would allow them to maximize performance during another 10km race. Because 5km is half the distance of 10km, it may be logical to presume only 24 hrs of passive recovery may be needed, instead of the required 48 hrs for 10km. However, this hypothesis was not supported when we tested two distance runners of above average abilities in a pilot study as the participants were not able to achieve similar 5km performance after 24 hrs of passive recovery. Twenty-four hours may not be a sufficient amount of time for the dissipation of muscle fatigue or soreness (Brown & Henderson, 2002). Therefore, the purpose of this study was to compare 5km running performance after 24 hrs of passive recovery versus 72 hrs of passive recovery.
Methods
Participants
Participants for the study were 12 well trained male (n = 9) and female (n = 3) runners currently engaged in rigorous training. Runners from the local road running and track club, local triathlon competitors, and former competitive high school and college runners, were recruited by word of mouth. Participant inclusion criteria included: (a) Subjects must have been currently involved in a distance running training program, (b) Had previously run 16-22 min for male runners or 18-24 min for a female runner for 5km, (c) Currently averaging at least 20-30 miles (running) per week, (d) Have previously completed at least five 5km road or track races, (e) Have a VO2max of at least 45 ml/kg/min (females) or 55 ml/kg/min (males), and (f) Provided sufficient data (from running history questionnaires, Physical Activity Readiness Questionnaires, and Health Readiness Questionnaires) that reflected good health.
Participants completed a short questionnaire regarding their running background, racing history, and current training mileage. All participants were volunteers and signed a written informed consent outlining requirements and potential risks and benefits resulting from participating.
Procedures
Participants were assessed for age, height, body weight, and body fat percent using a 3-site skinfold technique (Brozek & Hanschel, 1961; Pollock, Schmidt, & Jackson, 1980). Participants were fitted with a Polar Heart Rate Monitor and then completed a graded exercise test (GXT) to exhaustion lasting approximately 12-18 minutes. VO2max, heart rate (HR), and Ratings of Perceived Exertion (RPE) were collected every minute.
All GXTs were completed on a Quinton 640 motorized treadmill. The test began with a 2 min warm-up at 2.5 mph. Speed was increased to 5 mph for 2 min, followed by 2 min at 6 mph, 2 min at 7 mph, and 2 min at 7.5 mph. At this point, incline was increased two percent every 2 min thereafter until the participant reached volitional exhaustion (ie., the felt like they could no longer continue running at the required speed and grade). Once the participant reached volitional exhaustion, they were instructed to cool down until they felt recovered.
Approximately five days later, participants performed their first 5km race between the hours of 6:30 am and 7:30 am. The time of day for each performance trial was consistent throughout the study. All performance trials were completed on a flat hard-surfaced 0.73 mile loop. Prior to each trial, participants completed visual analog scales pre and post a 1.5 mile warm-up run, regarding their feelings of fatigue and soreness within the quadriceps, hamstrings, gastrocnemius, lower body, and total body muscle groups. Visual analog scales were 15 cm lines where participants placed an “X” on the line indicating their feelings (with 0 = no fatigue or soreness and 15 = extreme fatigue or soreness). The visual analog scales evaluated participants’ status before the start of every time trial. Participants were also required to rate their perceived exertion (RPE) after the warm-up, prior to the start and during each 5km, to see if feelings of effort remained consistent between each trial, as well as during each lap and after each performance trial.
Participants underwent a 1.5 mile warm-up prior to every 5km performance trial (Kaufman & Ware, 1997). Participants completed successive 5km performance trials on two separate occasions. Immediately following a baseline 5km trial, runners recovered passively for 24 hrs (R24) or 72 hrs of passive recovery (R72) and then performed a second 5km trial. The 5km time trial sessions were in a counterbalanced order and were separated by 6-7 days of normal training. All participants were required to have 24 hrs of passive recovery prior to each baseline. Passive recovery was deemed as no exercise or extensive physical activity during the allotted recovery hours. During each time trial, average HR (HRave) and ending RPE (RPEend) were recorded to determine if effort for each 5km trial was consistent. All runners competed with runners of equal ability to simulate race day and hard training conditions with verbal encouragement provided often and equally to each participant. At the end of every performance trial, each runner was instructed to complete a low intensity 1.5 mile cool-down. Each testing session required approximately 60 min.
Statistical Analysis
Basic descriptive statistics were computed along with Repeated Measures of Analysis of Variance (MANOVA) for making comparisons between R72 and R24 performance trials regarding finishing times, HRave, RPEend, and fatigue/soreness responses. All statistical comparisons were made at an a priori p < 0.05 level of significance. Data was expressed as group mean + standard deviation and individual results.
In order to evaluate individual responses, data from each participant’s first 5km trial was compared to their second 5km trial using a paired T-test. The least significance group mean difference (p < 0.05) was determined and group mean finishing time was adjusted to determine the amount of change in seconds, between baseline and treatment trials, needed for significance. The time change between the first trial run and the adjusted baseline run was divided by the first trial run and expressed as a mean number of seconds and as a percent for both the R24 (9.5 secs or 0.8%) and R72 (7.0 secs or 0.6%) trials. The percent values were applied to each individual baseline time in order to determine how many seconds (positive or negative) the second performance trial time had to be over or under the first performance trial, in both R24 and R72 conditions, to quantify as a response. Participants were then labeled as non-responders, positive-responders (faster during successive trial), and negative-responders (slower during successive trial).
Results
Descriptive characteristics are found in Table 1. The participants were between the ages of 18 and 35 (majority of subjects were between ages of 20-28) years. All participants were trained runners or triathletes (where running was their specialty event).
Table 1
Participant (Males = 9 & Females = 3) Descriptive Statistics
Mean Standard Deviation
________________________________________________________________________
Males Females Group Males Females Group
|
Age (yrs) |
25.6 |
22.0 |
24.7 |
5.0 |
1.0 |
4.6 |
|
Height (cm) |
175.3 |
168.0 |
173.5 |
6.2 |
18.2 |
10.0 |
|
Weight (kg) |
78.0 |
61.7 |
73.9 |
10.9 |
10.0 |
12.6 |
|
Body Fat (%) |
10.9 |
21.9 |
13.7 |
1.3 |
2.0 |
5.1 |
|
VO2max (ml/kg/min) |
63.3 |
59.7 |
62.4 |
5.0 |
7.9 |
5.6 |
|
Pre-study 5km Personal Best (min) |
18:57 |
21:31 |
20:19 |
1:54 |
2:05 |
2:02 |
|
Average Weekly Mileage |
31.7 |
30.1 |
30.5 |
7.4 |
7.7 |
7.5 |
|
Days Per Week |
4.9 |
4.6 |
4.7 |
1.5 |
1.1 |
1.2 |
________________________________________________________________________
Mean finishing times, HRave, and RPEend for 1) R24 vs baseline and 2) R72 vs baseline are found in Table 2. R24 was significantly (p = 0.03) slower (10 secs) than baseline, where as R72 was not significantly (p = 0.21) different from baseline. Regarding HRave, no significant differences (p = 1.00) were found between R24 and baseline, yet R72HRave was significantly (p = 0.04) greater than baseline. Significance (p = 0.39) was not found between R24 RPEend and baseline, but R72 RPEend was significantly (p = 0.01) higher than baseline.
Table 2
Comparison of R24 (24 hrs) vs R72 (72 hrs) Trials
________________________________________________________________________
Baseline R24 Baseline R72
________________________________________________________________________
|
Finish Time (min) |
19:49 + 1.9 |
19:59 + 1.9* |
19:34 + 1.6 |
19:30 + 1.5 |
|
Average HR (b/min) |
177.3 + 7.3 |
177.3 + 6.3 |
175.4 + 6.5 |
177.9 + 6.3* |
|
Ending RPE |
19.6 + 0.8 |
19.5 + 0.8 |
19.3 + 0.9 |
19.8 + 0.6* |
________________________________________________________________________
R24 trials = 24 hrs of passive recovery between baseline and R24
R72 trials = 72 hrs of passive recovery between baseline and R72
*indicates significant difference between respective baseline trial.
Figure 1 displays individual differences between R24 and R72 performance trials. To be considered a non-responder, the individual time change had to fall within 0.8% of baseline performance for R24 and 0.6% of baseline performance for R72.
Figure 1. Changes in Individual Finishing Times (R72 vs R24)
Positive and negative responders (Table 3) were identified when individual time change was greater than 0.8% for R24 trials and 0.6% for R72 trials, with a positive responder being one whose 2nd performance trial time improved (expressed as a negative value) and a negative responder being one whose 2nd performance trial time slowed (expressed as a positive value).
Table 3
Comparison of Individual R24 and R72 Performance Trials
________________________________________________________________________
Participant Baseline R24 Time Baseline R72 Time
(min) (min) Change (min) (min) Change
(secs) (secs)
________________________________________________________________________
|
1 |
16:41 |
17:06 |
+25* |
16:42 |
16:36 |
-6* |
|
2 |
17:38 |
17:17 |
-21* |
17:25 |
17:32 |
+7* |
|
3 |
17:44 |
17:50 |
+6* |
17.44 |
17:37 |
-7* |
|
4 |
18:58 |
19:13 |
+15* |
18:38 |
18:48 |
+10* |
|
5 |
19:00 |
19:11 |
+11* |
20:05 |
20:08 |
+3 |
|
6 |
19:05 |
19:38 |
+33* |
19:35 |
19:49 |
+14* |
|
7 |
20:17 |
20:09 |
-8* |
19:49 |
19:48 |
-1 |
|
8 |
21:01 |
21:14 |
+13* |
20:13 |
20:05 |
-8* |
|
9 |
21:05 |
21:21 |
+16* |
20:49 |
20:37 |
-12* |
|
10 |
21:53 |
22:24 |
+31* |
21:30 |
20:36 |
-54* |
|
11 |
22:07 |
21:56 |
-11* |
21:14 |
21:20 |
+6 |
|
12 |
22:18 |
22:25 |
+7* |
21:05 |
21:02 |
-3
|
|
MEAN |
19:49 |
19:59@ |
9.8 |
19:34 |
19:30 |
-4.3 |
________________________________________________________________________
R24 trials = 24 hrs of passive recovery between R24 and baseline
R72 trials = 72 hrs of passive recovery between R72 and baseline
* = responder
– = faster
+ = slower
@ = significance
Three individuals responded negatively to R72 by running a mean 10.3 + 5.7 secs slower during R72. Five individuals responded positively to R72 by running a mean 17.4 + 22.9 secs faster than baseline. Four individuals were considered non-responders to R72 with a mean time change of 3.3 + 1.8 secs.
Nine individuals responded negatively to R24 by running a mean 17.4 + 12.1 secs slower than baseline. Three individuals responded positively to R24 by running a mean 13.3 + 6.8 secs faster. There were no non-responders to the R24 trials. It is important to note that only two (participants 3 and 10) of three individuals who were negative responders to R72 also responded negatively to R24. Also, there were no individuals who positively responded to both R72 and R24.
There were no significant differences between R24 and baseline trials vs R72 and baseline trials for soreness and fatigue regarding pre and post warm-up scores on the fatigue/soreness visual analog scales (Table 4).
Table 4
Soreness and Fatigue Responses: R24 vs R72 Trials
________________________________________________________________________
Pre Warm-up Post Warm-up
________________________________________________________________________
________________________________________________________________________
No significant differences were found between trials
Subjects appeared to be fully recovered before each trial
Discussion
The primary purpose of this study was to compare 5km racing performance after 24 hrs of passive recovery versus 72 hrs of passive recovery. Other than a few somewhat related studies by Bosak et al. (2008 & 2009), the necessary duration of passive recovery from 5km time trials has not previously been studied. Results indicate that 72 hrs of passive recovery, on average, permits maintenance of second 5km time trial performance, yet individual variability existed regarding rate of decline of 2nd trial performance. Individuals must therefore test themselves or coaches must test their athletes to determine optimal recovery time that allows for improved performance during successive 5km efforts.
R24 was significantly (p = 0.03) slower (10 secs) than baseline. However, no significant differences (p = 0.21) occurred between R72 and baseline (Table 2). Due to the catabolic nature of the running process, pain results from microtears and swelling (edema) within the muscle, which require sufficient passive recovery time prior to undergoing another intense running effort (Brown & Henderson, 2002). Increased passive recovery time can also be used to reduce the reflex muscle spasm and spastic conditions that accompany pain. Thus, it is logical to assume longer hours of passive recovery following a 5km race, may attenuate soreness and fatigue prior to the next race or hard running effort, which would potentially allow performance to be maintained or at least minimize impairment (Fitzgerald, 2007). Therefore, in this study, it is hypothesized that 72 hrs of passive recovery facilitated a more effective recovery allowing participants to actually run a few seconds faster than baseline. Since, subjects were required to have 24 hrs of passive recovery before each baseline it is likely that subjects were more fully recovered for R72 than for either baseline performance trial, thereby producing slight improvements during R72 performance trial.
There were no significant differences between R24 and baseline trials versus R72 and baseline trials for soreness and fatigue (Table 4) regarding pre and post warm-up scores on the fatigue/soreness visual analog scales. These results indicated that all runners tended to feel the same prior to each baseline and treatment trial. The assumption, therefore, is that each runner felt a similar level of preparedness before every trial. However, individual variability (Figure 1) existed among runners, which makes it important to focus on the effects of passive recovery (24 hrs and 72 hrs) on each individual.
Four individuals were considered non-responders to R72 with a mean time change of positive or negative 3.3 + 1.8 secs. It is possible that the intensity needed to complete the 5km performance trial was less than what was needed to fatigue these 4 non-responders.
Five individuals responded positively (Table 3) to R72 running a mean of 17.4 + 12.9 secs faster during the second trial. The potential reason for improved performance during R72 may be due to the fact that the 5 participants may have been in a more rested state as compared to their status prior to the first trial. Several of those subjects who did run faster during R72 verbally indicated that they “felt better” (regarding fatigue and muscle soreness) prior to the start of the second 5km as compared to how they were feeling before the baseline trial.
Despite the fact that as a group the participants ran a mean 10 seconds slower during R24 vs baseline, three individuals responded positively to R24 by running a mean 13.3 + 6.8 secs faster than baseline. The improvements during R24 could have been due to the fact that the 5km distance may not have been sufficient enough to fatigue these individuals from baseline, which allowed each runner to be recovered before the start of the second trial.
In terms of participants who ran slower (Table 3) during R24 and R72 performance trials, 9 individuals ran a mean time of 17.4 + 12.1 seconds slower after 24 hrs of passive recovery. Apparently, 24 hrs of passive recovery was not sufficient enough to allow muscle function to return to normal (Brown & Henderson, 2002). However, despite having 72 hrs of passive recovery, 3 participants still ran a mean of 10.3 + 5.7 secs slower than baseline. The decreased performance during R72 may have been a result of the runners having a “feeling of staleness” in their legs from completing no exercise for 72 hrs as explained by Mujika et al. (2001), where he suggested that many collegiate and post-collegiate runners often complain of feeling “stale” if they haven’t run in a few days. A potential loss of “feel” during exercise has been implied to occur in competitive athletes as a result of a reduction in training frequency (Mujika et al., 2001).
Despite R72 HRave being significantly (p = 0.04) greater than baseline and R24 HRave being the same as baseline, there were no consistent patterns of HRave and increased or decreased performance among participants during all R72 and R24 trials. It can be assumed that a lower HRave was associated with less effort since HR and intensity levels are related. However, only participant 7 ran faster and had a higher HRave during R24 and R72. During the R72 trials, only participants 4, 10, and 12 ran slower and had a lower HRave during second trial performance. During the R24 trials, only 1, 3, 5, 6, ran slower and had a lower HRave during second trial performance.
As for RPEend, no significant difference (p = 0.40) occurred between R24 and baseline, yet R72 was significantly (p = 0.01) greater than baseline. Also, scores on the pre and post warm-up fatigue/soreness visual analog scales were not significantly different between R24 and baseline trials vs R72 and baseline trials, indicating that all runners individually tended to feel the same prior to each 5km trial. Therefore, since inconsistencies exist between HRave, RPEend, and performance trials, while no significant differences occurred regarding fatigue/soreness responses, it is assumed that all participants displayed similar efforts during each 5km performance trial.
Conclusion
The results of the study indicate that 72 hrs of passive recovery, on average, permits maintenance of second day 5km performance. The study displays evidence that in most runners, 24 hrs of passive recovery did not provide sufficient recovery time for restoration of proper muscle function in agreement with Foss and Keteyian (1998) and Sinclair, Olgesby, & Pierpenburg (2003). For most runners, performance after 24 hrs of passive recovery may be impaired due to the inability to recruit sufficient muscle fibers in active muscles, as a result of residual muscle fatigue (Noakes, 2003). On average, more than 24 hrs of passive recovery is necessary for most runners to achieve optimal 5km race performance (Bosak et al., 2008). Since it was apparent that individual variability in recovery occurred in our study, individuals and coaches must therefore test themselves and their athletes to determine optimal recovery time, which may vary even within individuals depending upon other factors.
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Authors’ References:
- Dept. of Sport Health Science, Life University, Marietta, GA 30060
- Dept. of Kinesiology, University of Alabama, Tuscaloosa, AL 35401
- Dept. of Health, PE, and Recreation, University of North Alabama, Florence, AL 35632
- Dept. of Health and Human Performance, Georgia Southwestern State University, Americus, GA 31709
- Dept. of Health, Exercise Science, and Secondary Education, Lee University, Cleveland, TN 37320
