The Off-Season Strength Block: How Much You Can Build Now, and How Little Keeps It

October is when many age-group triathletes finish their season and start thinking about next year. TriForward's "The Off-Season" covers the first part of that decision: how much rest you can take before fitness slips. This article is about what comes next. If you want to get stronger this winter, how much should you do, for how long, and what's the least you can do in spring and summer to hold on to it?

The evidence here is mostly from cyclists and from general adults rather than triathletes, and the trials are small. But it gives a consistent outline: build with two heavy sessions a week over a few months, then maintain with one, keeping the weights heavy even as the volume drops.

TriForward's "The Minimum Effective Dose" covers how little strength training a time-crunched triathlete needs in general. This piece focuses on the seasonal structure: a building block followed by maintenance.

Why the off-season suits a strength block

Three features of winter make it the natural time to build strength:

• Endurance volume is usually lower. Fewer long rides and runs leave more recovery for lifting.
• No races are close. The first weeks of a new strength programme often cause soreness that can disrupt training. In winter, that matters less.
• There's time for slow adaptations. Strength and muscle changes take weeks to months, so starting early means the gains are in place before race-specific training begins.

The first point has some direct evidence behind it. A 2012 trial by Rønnestad, Hansen and Raastad in the European Journal of Applied Physiology compared 11 well-trained cyclists who added heavy strength training twice a week to a high volume of endurance training for 12 weeks with 7 people who weren't endurance-trained doing the same lifting alone. Both groups increased strength, thigh muscle size and squat jump performance, but the relative gains were larger in the lifting-only group.

Inference: this suggests that heavy endurance training reduces the response to lifting. The groups differed in more than training volume, so it isn't conclusive, but it fits with planning a strength block when endurance volume is lower. TriForward's guide "Lifting and Endurance in the Same Week" covers the wider interference evidence.

How much you can build: the cycling evidence

The best evidence for strength training improving bike performance comes from cyclists. TriForward's guide "Heavy Lifting for Bike Power" covers it in detail. In brief:

• A 2025 meta-analysis by Llanos-Lagos and colleagues pooled 17 studies with 262 endurance cyclists, 60 of them women. Programmes lasted 5 to 25 weeks with 1 to 3 sessions a week. Heavy strength training improved time-trial and time-to-exhaustion performance (effect size 0.463) and efficiency, without changing VO2max. The certainty of the evidence was rated low, and the authors found no clear effect of programme length or frequency.
• A 2016 trial by Vikmoen and colleagues found that 19 well-trained female cyclists who added heavy lifting for 11 weeks improved 40-minute all-out power and cycling economy, compared with endurance training alone.
• A 2015 trial by Rønnestad and colleagues in 16 young elite cyclists found that 25 weeks of heavy strength training improved 40-minute power and power at 4 mmol/L lactate more than endurance training alone.

Inference: most of the clearly positive trials ran for 11 weeks or longer with twice-weekly sessions. A three-month block from the end of the off-season break to early spring fits that pattern for a typical northern-hemisphere race calendar.

The trial that tested build then maintain

The most directly relevant study for seasonal planning is a 2010 trial by Rønnestad, Hansen and Raastad in the European Journal of Applied Physiology (volume 110). It followed well-trained cyclists through a winter build and into the race season.

• Strength group: 6 cyclists, all men.
• Endurance-only group: 6 cyclists, 5 men and 1 woman.
• Preparatory period: the strength group added heavy strength training twice a week for 12 weeks.
• Competition period: the strength group then did strength maintenance training once a week for the first 13 weeks of the race season.

The results:

• After the 12-week build, the strength group had increased thigh muscle size and one-repetition maximum, while the endurance-only group hadn't. Both groups had improved VO2max and 40-minute all-out power.
• At 13 weeks into the race season, the strength group had preserved the increases in muscle size and strength from the winter.
• From the start of the build to week 13 of the season, the strength group improved Wingate peak power, power at 2 mmol/L lactate, maximal aerobic power and 40-minute mean power. The gains in the last two were larger than in the endurance-only group. The endurance-only group showed no change in maximal aerobic power or power at 2 mmol/L lactate.

Six cyclists per group is a very small sample, and nearly all were men. But the design matches what many triathletes would actually do: build in winter, maintain in season. It suggests that one weekly session is enough to keep the gains, and that the benefits for bike power carried through into the race season rather than fading.

How little keeps it: the maintenance evidence

The cycling trial is supported by research in general adults.

The Bickel trial. A 2011 study by Bickel, Cross and Bamman in Medicine & Science in Sports & Exercise trained 70 adults, aged either 20 to 35 or 60 to 75, three days a week for 16 weeks. They were then randomised for 32 weeks to stop training or to continue at one-third or one-ninth of the original dose.

• Strength gains were largely retained through the maintenance period, with only a slight reduction by the end.
• Both maintenance doses kept muscle size in younger adults, and the one-third dose produced some further growth.
• Older adults didn't maintain muscle size on either reduced dose, although their strength stayed above that of untrained young adults.

TriForward's "The Minimum Effective Dose" also draws on this trial.

The Spiering review. A 2021 review by Spiering, Mujika, Sharp and Foulis in the Journal of Strength and Conditioning Research pulled together maintenance research, mostly in general populations. It concluded that strength and muscle size can be maintained for up to 32 weeks with one session a week and one set per exercise, as long as the relative load is maintained, in younger people. Older adults may need two sessions a week with two to three sets. The authors noted there's little data in athletes.

Inference: the common thread is that load matters more than volume. You can cut the number of sessions, sets and exercises substantially, but the weight on the bar needs to stay heavy relative to what you can lift.

What happens if you stop completely

A 2013 meta-analysis by Bosquet and colleagues in the Scandinavian Journal of Medicine & Science in Sports included 103 studies on stopping strength training. It found:

• Maximal force declined (standardised mean difference −0.46).
• Power declined less (−0.20).
• Submaximal strength declined most (−0.62).
• Losses grew with the length of the break and were larger in people over 65.

TriForward's "The Off-Season" covers this meta-analysis in the context of a winter break. In this context, the point is that dropping strength training completely from spring to autumn is likely to lose a meaningful part of what you built over winter, particularly for older athletes.

Who was studied, and who wasn't

Before turning this into a plan, it's worth being clear about the gaps:

• The build-then-maintain trial had 12 cyclists, 11 of them men. It's the only study here that tested the full seasonal pattern.
• Women are better represented in the building evidence than the maintenance evidence. The 2025 meta-analysis included 60 women among 262 cyclists and found no difference by sex, and the 11-week trial in 19 female cyclists was positive. No maintenance trial in female endurance athletes was found.
• The maintenance research in older adults isn't in athletes. The Bickel trial and much of the Spiering review studied general adults, not people also doing a lot of endurance training.
• None of these studies involved triathletes, who carry running and swimming load alongside the bike.

Inference: the outline of build and maintain is consistent across these sources, but the exact numbers, such as 12 weeks or one session a week, are best treated as starting points rather than proven doses for triathletes.

Tracking progress during the block

Strength changes are easier to measure than bike changes. Some simple, low-cost ways to judge whether the block is working:

• Log your working weights. If the load for the same number of repetitions rises over the weeks, you're getting stronger.
• Retest bike power at the end of the block, not after the first few weeks. Most of the positive trials ran for 11 weeks or longer.
• Note how your legs feel on the bike. Persistent heaviness on key sessions suggests the lifting needs to move further from them, or the endurance load needs trimming.
• Keep the same exercises long enough to progress. Changing exercises every week makes it hard to know whether you're getting stronger.

Planning the build phase

These suggestions combine the trials above. They're inference for triathletes, not a tested programme:

1. Take your break first. Start the strength block after your off-season rest, not instead of it.
2. Spend two to three weeks on technique. Use light loads to learn or relearn squats, deadlifts or leg press, split squats and calf raises.
3. Build to two heavy sessions a week. The cycling trials used lower-body exercises in sets of around 4 to 10 repetitions, with loads close to the limit for that number.
4. Plan for about 10 to 12 weeks of heavy work. Most of the clearly positive trials ran for 11 weeks or longer.
5. Keep endurance volume moderate during the block. Inference from the 2012 trial: very high endurance volume may reduce your strength gains.
6. Keep some intensity in your endurance training. TriForward's "The Off-Season" covers how to hold aerobic fitness on reduced training.

Planning the maintenance phase

1. Drop to one session a week as race-specific training builds, typically in early spring.
2. Keep the weight heavy. Reduce the number of sets and exercises, not the load.
3. Masters athletes may need two sessions a week, at least for some of the season, based on the Bickel and Spiering findings in older adults.
4. Place the session away from key workouts, for example after an easy swim, at least two days before a hard bike or run session.
5. Reduce, don't stop, before races. Drop the session in race week if needed, but return to it afterwards rather than abandoning it for the summer.

A triathlon season

The following example is illustrative, not drawn from a study. A 50-year-old man finished his last 70.3 in early October and has a half-Ironman next June.

• October: two weeks of rest and easy activity, as covered in "The Off-Season".
• Late October to mid-November: two light strength sessions a week focused on technique, with easy endurance training.
• Mid-November to February: two heavy lower-body sessions a week, with moderate endurance volume and one or two harder bike sessions.
• March to June: one heavy session a week, with a second short session in some weeks because of his age, placed after easy swims.
• Race week: a lighter session early in the week, or none.

Common mistakes

• Starting heavy straight after the break. Severe soreness can cost a week of training.
• Lifting light for high reps all winter. The building trials used heavy loads.
• Stopping completely once the season starts. The losses are slower than for aerobic fitness, but they add up over months.
• Keeping two full sessions a week all season when race-specific training needs the recovery. One heavy session was enough to maintain gains in the cycling trial.
• Reducing the load instead of the volume in season. Maintenance depends on keeping the weights heavy.

What we don't know

• Whether these patterns hold in triathletes, who balance three sports rather than one.
• How much maintenance women and masters athletes need, given the small numbers in the cycling trials.
• The ideal length of the building block, which the 2025 meta-analysis couldn't identify.
• Whether maintenance holds for a full season beyond the 13 weeks tested in cyclists.
• Whether strength gains improve triathlon race results, which no trial has measured.

References

• Rønnestad BR, Hansen EA, Raastad T. In-season strength maintenance training increases well-trained cyclists' performance. European Journal of Applied Physiology, 2010;110(6):1269–1282. doi:10.1007/s00421-010-1622-4
• Rønnestad BR, Hansen EA, Raastad T. High volume of endurance training impairs adaptations to 12 weeks of strength training in well-trained endurance athletes. European Journal of Applied Physiology, 2012;112(4):1457–1466. doi:10.1007/s00421-011-2112-z
• Llanos-Lagos C, Ramírez-Campillo R, Sáez de Villarreal E. Heavy strength training effects on physiological determinants of endurance cyclist performance: a systematic review with meta-analysis. European Journal of Applied Physiology, 2026;126(1):193–222 (online 2025). doi:10.1007/s00421-025-05883-2
• Vikmoen O, Ellefsen S, Trøen Ø, Hollan I, Hanestadhaugen M, Raastad T, Rønnestad BR. Strength training improves cycling performance, fractional utilization of VO2max and cycling economy in female cyclists. Scandinavian Journal of Medicine & Science in Sports, 2016;26(4):384–396. doi:10.1111/sms.12468
• Rønnestad BR, Hansen J, Hollan I, Ellefsen S. Strength training improves performance and pedaling characteristics in elite cyclists. Scandinavian Journal of Medicine & Science in Sports, 2015;25(1):e89–e98. doi:10.1111/sms.12257
• Bickel CS, Cross JM, Bamman MM. Exercise dosing to retain resistance training adaptations in young and older adults. Medicine & Science in Sports & Exercise, 2011;43(7):1177–1187. doi:10.1249/MSS.0b013e318207c15d
• Spiering BA, Mujika I, Sharp MA, Foulis SA. Maintaining physical performance: the minimal dose of exercise needed to preserve endurance and strength over time. Journal of Strength and Conditioning Research, 2021;35(5):1449–1458. doi:10.1519/JSC.0000000000003964
• Bosquet L, Berryman N, Dupuy O, Mekary S, Arvisais D, Bherer L, Mujika I. Effect of training cessation on muscular performance: a meta-analysis. Scandinavian Journal of Medicine & Science in Sports, 2013;23(3):e140–e149. doi:10.1111/sms.12047