Research · Season Programming

Build It in the Off-Season, Keep It In-Season: What the Research Actually Shows

By Muhammad Dzulhisham · MSc Sports Coaching, NSCA-CSCS

Two failure modes show up in almost every school or club team's annual calendar. The first: the strength program that ran all off-season gets quietly dropped the week fixtures start, on the assumption that practice and games are "enough" and the weight room would just add fatigue on top. The second: the exact opposite mistake — the off-season's training volume gets carried straight into the season, on the assumption that more is always better, until an athlete is trying to recover from a heavy squat session, two field sessions, and a match inside the same 96 hours.

Both approaches are guesses. What the periodization and dose-response literature actually shows is that the off-season and the in-season are supposed to be doing two different jobs — one is for building a physical quality, the other is for protecting it — and the amount of training that each job actually requires is now reasonably well measured.

The seminal test: how little strength training does it take to hold the line?

The cleanest experiment on in-season strength maintenance is now 15 years old and still the reference point most reviews return to. Rønnestad, Nymark, and Raastad put a squad of professional soccer players through an identical 10-week pre-season strength program, twice weekly, then split them for the first 12 weeks of the competitive season: one group kept lifting once a week, the other dropped to once every two weeks — effectively half the volume of the first group.¹ The once-weekly group held onto the strength, jump, and 40-m sprint gains built in pre-season. The once-every-two-weeks group did not — a follow-up review of the same data reports an average 10% loss in 1RM half-squat strength over that 12-week stretch, alongside a measurable drop in sprint performance.²

That third figure comes from a separate line of research on minimum effective dosing. A 2021 review in the Journal of Strength and Conditioning Research on maintaining physical performance during periods of restricted training time concluded that intensity — how heavy the load actually is — is the variable that matters most for holding onto strength, and that frequency and volume can be cut substantially, in some cases to a single session, without losing ground, as long as that load stays high.³ A 2024 review in the NSCA's own Strength and Conditioning Journal, built around the concept of "microdosing" resistance training for team sports, cites that work directly: reductions in volume of roughly a third to two-thirds are tolerable for maintenance, "provided the load lifted remains high."⁴

Frequency and volume aren't the load-bearing variables — load is

A broader systematic review and meta-analysis, pooling 10 studies of well-trained populations over 6–12 week blocks, backs up the same conclusion from the other direction: once total training volume is equated, there's no meaningful difference in strength outcomes between training frequencies — a trivial, non-significant effect for both upper body (g = 0.088) and lower body (g = 0.061) strength.² The practical takeaway the authors draw for in-season programming is that a coach has real flexibility to redistribute the same volume around a congested fixture list — shorter, more frequent sessions instead of one or two long ones — without a strength cost, as long as the intensity of the actual lifting doesn't drop.

This is the logic behind "microdosing" as a programming strategy: instead of asking whether to lift in-season or not, divide the volume a microcycle would normally carry into smaller, more frequent doses, and place the heavier, longer session furthest from the next game and the lighter, shorter one closest to it. The aim is to keep enough stimulus in the week to prevent the specific physical qualities from decaying — what the sport-science literature calls "training residuals" — without stacking additional fatigue on top of a schedule that already includes practice and competition.⁴

The same pattern holds in school-age athletes, not just professionals

The Rønnestad data is professional and adult, which raises a fair question for a program built around school and youth athletes: does the same minimal-dose logic apply to a 15-year-old in a school season? A 2024 study in the Journal of Human Kinetics ran essentially the same comparison directly in that population — 23 high school girls' basketball players, mean age 15.2, split into once-weekly and twice-weekly in-season strength training groups over a 6-week competitive block.⁵ The result matched the professional data: grip strength, leg and back strength, medicine-ball throw distance, vertical jump, and change-of-direction performance all improved similarly in both groups, with no meaningful advantage for training twice a week over once.

A 2025 systematic review and meta-analysis in Sports Medicine – Open, pooling 17 studies across team sport players broadly, reached a similar conclusion at a larger scale: lower-volume resistance and running-based training produced statistically comparable improvements in jumping, sprinting, and change-of-direction performance compared to higher-volume training, with an overall effect size for resistance training close to zero (−0.05, 95% CI crossing zero).⁶ The review's authors are candid that the certainty of this evidence is still rated very low, given small samples and methodological limitations across the underlying studies — a caveat worth taking seriously rather than treating "less is fine" as a settled fact. But the direction of the finding, across a professional soccer squad, a high school basketball team, and a pooled review of team-sport athletes generally, is consistent: in-season, a small, well-loaded dose does the maintenance job a much larger one was assumed to be needed for.

The competitive season was never built to develop a physical quality from scratch. Its evidence-backed job is narrower and more achievable: protect what the off-season already built, using a fraction of the volume that built it.

Which means the off-season has to actually do its job

None of this is an argument for training less overall — it's an argument for training the right amount in the right window. If one high-intensity session a week is genuinely enough to hold strength through a season, the off-season is where any real change in strength, power, or work capacity has to come from, because the season itself was never going to produce it. That puts real weight on how the off-season block is actually structured.

The NSCA's own supplemental guidance on periodization for team sports lays out a preparatory period built from two phases with distinct jobs. The general preparation (GP) phase comes first: building basic physical capacity, restoring or improving strength, and re-establishing a fitness base, with a recommended minimum of 25% of the total preparatory period allocated here and no more than 40% of that training considered high-intensity.⁷ Only once that foundation is in place does the specific preparation (SP) phase take over, where sport-specific, competition-related training rises to 70–80% of programming, with the remaining 20% or so devoted to maintaining the broader athletic qualities the GP phase just built.⁷

The same guidance is specific about a detail that matters for a school or youth program in particular: younger, less-trained athletes are recommended a longer general preparation allocation than an advanced or professional athlete gets, not a shorter one — because the physical foundation being built has further to go and takes longer to establish properly. It also echoes a caution worth repeating for anyone tempted to schedule a tournament into the middle of a young athlete's off-season block: genuine competition during this phase works against the purpose of the phase, since the accumulated fatigue that comes with meaningful competition undercuts the very adaptation the block exists to produce.⁷

What this means for programming a youth team-sport athlete's year

Put together, the evidence points to a straightforward division of labor across the calendar rather than a single "best" approach that applies year-round. The off-season is the block where strength, power, and general physical capacity actually get built — long enough, particularly for a developing athlete, to do that properly, and structured so that easier, foundational work comes first and sport-specific intensity ramps up only once that foundation is in place. The in-season is not the block to try to repeat that work in. Its job, and the job the current evidence says it can actually do well, is maintenance: one — occasionally two — genuinely well-loaded sessions a week, positioned around the fixture list rather than fighting it, aimed at holding on to what the off-season built rather than adding to it.

The mistake in both directions comes from treating the season as one continuous block that should look the same in October as it does in June. It shouldn't. A program that quietly disappears the moment the whistle blows leaves real, measurable strength on the table over a season — the once-every-two-weeks group's 10% strength loss is not a trivial number for an athlete relying on that strength for contact, change of direction, or injury resilience. A program that keeps pushing off-season volume once games start is asking a tired, already-loaded athlete to absorb a training stimulus research says isn't even necessary to hold the line. The evidence-backed middle is smaller than either instinct: build properly when there's room to, and protect what was built with far less than most programs assume is required once the season starts.