After a twice-weekly winter strength block, one heavy session a week can maintain the strength and muscle gained, provided the load stays heavy
Interpretation
The only endurance-athlete trial of the full pattern (Rønnestad et al. 2010; 12 well-trained cyclists, 11 men) found 12 weeks of twice-weekly heavy lifting followed by one session a week preserved thigh CSA and strength through 13 weeks of racing, with larger gains in 40-min power and Wmax than endurance-only riders. Bickel et al. 2011 (70 general adults) and Spiering et al. 2021 (review, mostly general populations) support holding strength with about one session a week if relative load is kept, with older adults likely needing two. Graded limited because the athlete evidence is one very small, mostly male trial and the rest is from non-athletes.
Practical implication
Build with two heavy sessions a week for roughly 10–12 weeks in winter, then maintain with one heavy session a week in season, cutting sets rather than load; masters athletes may need two. These are starting points extrapolated from cyclists and general adults, not tested triathlon doses.
Sources
8 sources, independently verified.
Heavy strength training twice a week in a 12-week preparatory period, then once a week for the first 13 weeks of the competition period. After the preparatory period the strength group had increased thigh CSA and 1RM (no change in endurance-only group). At week 13 of competition the strength group had preserved those gains, and from start to week 13 improved Wingate peak power, power at 2 mmol/L lactate, Wmax and 40-min all-out mean power, with larger relative gains in the last two than the endurance-only group. Very small sample, nearly all men.
Both groups did heavy strength training twice a week for 12 weeks. Both increased 1RM, thigh muscle CSA and squat jump performance, but relative improvements were greater in the strength-only group; peak rate of force development improved only in the strength-only group. Non-randomised comparison of different populations; abstract read on SPONET, metadata on OpenAlex.
Heavy strength training (≥80% 1RM or ≤7RM; 5–25 weeks, 1–3 sessions/week) added to endurance training improved time-trial/time-to-exhaustion performance (ES 0.463), cycling efficiency (ES 0.353) and anaerobic power (ES 0.560), with no significant effect on VO2max, power at VO2max, maximal metabolic steady state or anaerobic capacity. No significant moderators (sex, performance level, strength-training experience, duration, frequency). GRADE certainty low. Published online 2025 (issue 2026;126(1):193–222). Cyclists only, no triathletes; FTP not measured directly.
11 weeks of added heavy strength training increased leg press 1RM and quadriceps CSA and improved 40-min all-out mean power, fractional utilisation of VO2max and cycling economy; muscle fibres shifted from IIAX-IIX towards IIA. Individual 40-min gains correlated with quadriceps CSA change (r=0.73) and fibre-type change (r=−0.63). No changes in the endurance-only group.
25 weeks of heavy strength training improved half-squat strength, Wingate peak power, power at 4 mmol/L lactate and 40-min all-out mean power; gains in power at 4 mmol/L and 40-min power were larger than in the endurance group. Peak torque occurred earlier in the pedal stroke, which correlated with 40-min improvement (r=0.66). Neither group changed VO2max or cycling economy.
16 weeks of resistance training 3 days/week, then 32 weeks randomised to detraining or maintenance at one-third or one-ninth of the dose. Strength gains were largely retained with only a slight reduction by the end; both maintenance doses preserved hypertrophy in younger adults (one-third dose produced further growth) but not in older adults, whose strength nonetheless stayed above untrained young adults. Online 2010.
Endurance fitness can be maintained for up to 15 weeks with as few as 2 sessions/week, or with volume cut 33-66%, provided intensity (heart rate) is maintained; strength and size can be held for up to 32 weeks with just 1 session/week at 1 set per exercise in younger people, though older adults likely need 2 sessions/week with more sets. Mostly drawn from general-population research, not athlete-specific data — flagged as a real evidence gap.
Strength losses with training cessation follow a clear dose-response relationship with time off: submaximal strength declines most (SMD -0.62), maximal force less (-0.46), and power least (-0.20) — losses were larger in people over 65 and in previously inactive people compared to recreational athletes. Useful counterpoint to the cardio-detraining data: strength holds up noticeably better than aerobic fitness during an off-season.