REF-1199 · Shepley et al., 1992 · Journal of Applied Physiology · Paper · PubMed

Should I rest completely the week before a race?

Probably not: in 9 runners a week of hard, low-volume running lifted time to fatigue 22%; easy running (+6%) and rest (−3%) did not significantly. Small crossover.

Blimited evidenceMeasured on highly trained athletes

Shepley and colleagues gave nine highly trained male middle-distance runners, after 8 weeks of training, three different 7-day tapers in random order, with 4 weeks of training between them: a high-intensity, low-volume taper (HIT), a low-intensity, moderate-volume taper (LIT) and a rest-only taper (ROT).

Before and after each taper they measured a treadmill run to fatigue at the speed of the runner's best 1500 m, quadriceps strength and contractile properties, muscle glycogen and citrate synthase from needle biopsies, total blood and red-cell volume by isotope labelling, and VO2max. VO2max did not change with any taper.

Time to fatigue rose significantly by 22% after HIT and did not change significantly after LIT (+6%) or ROT (−3%). Citrate synthase activity rose with HIT and fell with ROT; muscle glycogen rose after ROT and HIT; strength rose after all three; total blood volume rose after HIT and fell after ROT.

Our reading: the cleanest within-runner evidence that a week of short, hard, low-volume running can improve a race-pace effort when easy running and rest did not significantly change it (no between-taper test is given in the abstract); the sample is nine men, the test is time to exhaustion, and the abstract does not say whether HIT differed significantly from the other two or how much volume each taper contained.

Protocol

Participants: n = 9 male middle-distance runners, described as highly trained; age and performance level not given in the abstract.
Design: after 8 weeks of training, runners were randomly assigned to one of three 7-day tapers; after the first taper they trained for 4 weeks, did a second taper, trained 4 more weeks and did the third, so each runner completed all three.
Tapers: high-intensity low-volume (HIT); low-intensity moderate-volume (LIT); rest only (ROT). Weekly volume, session content and intensity of each are not given in the abstract.
Measures before and after each taper: treadmill run to fatigue at the velocity of each runner's best 1500-m time; voluntary isometric strength and evoked contractile properties of the quadriceps; muscle glycogen and citrate synthase activity (needle biopsies); total blood volume and red-cell volume (125I and 51Cr labelling); maximal O2 uptake.
Not in the abstract: absolute run times, the statistical test between tapers, order effects, diet control, and the red-cell-volume result.
A secondary description: Spilsbury et al. describe the Shepley and Houmard tapers as volume cut by about 85-90% with all taper training done as 100-500 m intervals (REF-1202, full text). That is their summary, not this paper's abstract.
A published comment: J Appl Physiol 1993;75(3):1433-5, doi 10.1152/jappl.1993.75.3.1433 (listed in PubMed as a comment on this paper; not read).

Key Results

Change from before to after each 7-day taper, as stated in the abstract (no SDs, CIs or P values are given there):

OutcomeHigh-intensity, low-volume (HIT)Low-intensity, moderate-volume (LIT)Rest only (ROT)
Time to fatigue at best-1500-m speed+22%, significant+6%, not significant−3%, not significant
VO2maxunaffectedunaffectedunaffected
Citrate synthase activityincreased significantlynot stateddecreased significantly
Muscle glycogenincreased significantlynot statedincreased significantly
Voluntary isometric strengthincreasedincreasedincreased
Total blood volumeincreased significantlynot stateddecreased (significance not stated in the abstract)
What the abstract does not show: whether the +22% after HIT differed significantly from LIT and ROT (each taper is compared with its own baseline), the effect of LIT on glycogen, citrate synthase and blood volume, and the red-cell-volume result (the abstract is cut off).

Mechanisms

Measured: with HIT, citrate synthase and total blood volume rose; with rest, both fell within 7 days; glycogen rose after both HIT and rest; VO2max was unchanged by all three.
Authors' interpretation: not available — the abstract is truncated before the conclusion.
Inference: rest also raised glycogen significantly but did not improve time to fatigue, so glycogen alone does not explain the HIT gain; keeping some intense work kept oxidative enzyme activity and blood volume rising rather than falling.
Inference: time-to-exhaustion tests amplify change: a 22% longer run at a fixed speed corresponds to a much smaller gain in race time (a general property of these tests; not computed in this study).

Practical Application

Should I rest completely the week before a race? Probably not: in 9 runners a week of hard, low-volume running lifted time to fatigue 22%; easy running (+6%) and rest (−3%) did not significantly. Small crossover.
Keep the intensity in the taper. This is direct within-runner evidence for the base's rule (SYNTH-34: "do not drop the intensity"), which until now leaned on a pooled optimum (REF-107), a narrative review (REF-110) and an across-study subgroup (REF-3492; between-subgroup P = 0.10), none of them a within-athlete comparison.
Rest days are not free: a week of rest only lowered total blood volume and citrate synthase. Short sessions on most days fit this better than whole days off (SYNTH-34's "short days instead of rest days"; the length of rest that starts to cost is not tested here).
Expect performance to change, not VO2max: VO2max did not change with any taper.
Do not copy the volumes from this card: the abstract does not give them; Spilsbury's summary of an 85-90% cut (REF-1202) is secondary.

Limitations

From a truncated abstract. The volumes of each taper, the between-taper statistics, the red-cell-volume finding and the conclusion are not available; the full text was not read.
Small. Nine men; a 22% change in time to fatigue can be significant while +6% is not, with the same nine runners; a difference in significance is not shown to be a significant difference.
Time to exhaustion, not a race. A run to fatigue at fixed speed exaggerates the size of a change relative to race time (inference; see Mechanisms).
Order and season. Three tapers spread over about 11 weeks; fitness may have changed between them (randomised order limits but does not remove this). Diet and blinding are not described in the abstract.
Old and single-site. 1992, one laboratory (McMaster University); not replicated in the base with the same three-arm design.
Funding and conflicts: not stated in the abstract.
How this entry was checked and changed
Why this level

crossover with n = 9 (under 15), each runner his own control; the full text could not be retrieved (the publisher's free archive was behind a bot check), and the published abstract stops before the red-cell-volume result and the authors' conclusion