Indoor rowing is the ultimate “hybrid” sport: you need a big aerobic engine, but you also need strength and power to make each stroke count, especially over 2k, 5k, and head-race style efforts. That creates a classic programming problem:

Can you train strength and endurance at the same time without one undermining the other?

That concern is usually labelled the interference effect (also called the “concurrent training effect”)—the idea that combining endurance work with resistance training can reduce strength/power gains compared with strength training alone (or, less commonly, reduce endurance adaptations compared with endurance training alone).

The good news for rowers: interference is real in some contexts, but it’s often smaller than people think, and it’s highly manageable when you programme intelligently.

What is the interference effect, really?

The interference effect entered the modern training conversation largely because of a landmark study by Hickson (1980), where participants doing a high dose of endurance + strength training saw strength gains plateau compared with strength-only training.

Since then, bigger picture evidence has been shaped by meta-analyses:

• A widely cited meta-analysis by Wilson et al. (2012) found concurrent training can reduce strength and hypertrophy gains depending on how endurance is done, with running tending to produce more interference than cycling.

• A more recent systematic review/meta-analysis (Huiberts et al., 2024) suggests the average interference on maximal strength is small, with important moderators like sex and training status (e.g., untrained people can respond differently than trained athletes).

• Another large meta-analysis (Schumann et al., 2022) concluded concurrent training generally does not compromise muscle size or maximal strength, but explosive strength/power can be more vulnerable—especially when sessions are close together or combined.

Indoor rowing places unique demands on both aerobic capacity and force production, which is why intelligent strength integration is essential for long-term indoor rowing training.

Rowing translation: if your goal is rowing performance, we care less about bodybuilding-style hypertrophy and more about max force, rate of force development, and repeatable power under fatigue. That’s exactly where “how you combine sessions” matters most.

Why rowers are a special case

Rowing isn’t like mixing squats with long, pounding runs. Indoor rowing endurance training is:

• Concentric-dominant and relatively low-impact compared with running

• Typically performed with high muscular involvement (legs + trunk + upper body), which can create local fatigue that spills into lifting (and vice versa)

So rowers are in a middle ground: you may get less interference than a runner, but you still need to manage fatigue very carefully because rowing recruits so much muscle mass.

What the rowing-specific research suggests

A few studies and applied papers are especially relevant:

1) Strength training can support rowing performance—if it doesn’t wreck the rowing work

An older but relevant trial on collegiate male rowers found resistance work did not produce statistically significant short-term improvements in 2,000m erg time versus comparators, but the direction of change suggested potentially meaningful performance improvements in practice.
Takeaway: you don’t add strength work because it magically drops 2k time in a few weeks—you add it because it can raise the ceiling for power, efficiency, and robustness over time, provided it’s integrated well.

2) Acute interference can happen when lifting is too fatiguing

A study on semiprofessional rowers tested different resistance-training protocols and found rowing erg performance was not significantly affected after low-fatigue protocols, but it declined after high-fatigue protocols (notably sets to failure).
This is huge for indoor rowers: the fastest way to “create interference” is to turn strength sessions into demolition workouts.

3) The “molecular” explanation is real—but it’s not destiny

At the muscle-cell level, endurance work can increase signalling pathways associated with mitochondrial adaptations (often discussed via AMPK/PGC-1α), while resistance work activates pathways associated with strength/hypertrophy (often discussed via mTORC1). There’s evidence of cross-talk that can blunt some resistance signalling when endurance stress is high or too close to lifting.
But: the practical levers—timing, intensity, and fatigue—often matter more than the biochemistry buzzwords.

The main drivers of interference for indoor rowing + strength

1) Fatigue is the real culprit (more than “cardio vs weights”)

Rowing is already a heavy muscular endurance demand. If you add strength training with:

• lots of sets,

• short rests,

• and frequent training to failure,

…you’ll often compromise the quality of key rowing sessions and/or blunt power development. The rowing-specific evidence above strongly supports this “fatigue-first” view.

Rule: if you want strength to help rowing, most lifting should leave you feeling like you could have done 1–3 more reps on your main sets.

2) Explosive power is more sensitive than maximal strength

Across concurrent training research, maximal strength and hypertrophy are often fairly resilient, while explosive outputs can take a bigger hit.

For rowers, that means:

• If you care about start power, high-rate changes, and sprint finishes, you should protect sessions that target speed-strength and avoid pairing them too closely with draining endurance work.

3) Session timing and sequencing still matter

Evidence syntheses on concurrent training repeatedly flag how close sessions are together (and whether they’re in the same session) as a practical moderator, particularly for power.

Practical default for rowers:

• If doing two-a-days, separate endurance and lifting by ~6+ hours when possible.

• If you must combine in one session, bias toward:

  • strength first when strength/power is the priority, or

  • endurance first when the day’s rowing quality is the priority (e.g., key threshold/interval session).

Programming principles that work well for indoor rowers

Keep strength training “high quality, low mess”

For most indoor rowers, the sweet spot is:

• 2 sessions/week (3 only for advanced athletes with excellent recovery)

• Heavy compound lifts + rowing-specific accessories

• Low-to-moderate total volume

• Rarely training to failure (especially in-season)

This aligns with research in rowers showing benefits of structured strength work alongside rowing, and it matches the rowing-specific findings that low-fatigue RT doesn’t meaningfully harm rowing performance acutely.

Use rowing intensity distribution to your advantage

Indoor rowing training is often built around:

• lots of low intensity (UT2 – Zone 1),

• some moderate/hard (UT1/threshold – Zone 2),

• a smaller amount of very hard interval work (VO2max – Zone 3).

Your “interference risk” is highest when you stack:

• heavy lower-body lifting too close to

• hard rowing intervals or threshold sessions.

So protect your key rowing days by placing heavy legs after the hard rowing day (or on the easiest aerobic day if separated well).

A practical weekly template for indoor rowers (2k–10k focus)

Here’s a simple structure that tends to work well for many athletes:

Mon – Strength (Lower focus)

• Heavy hinge and/or squat pattern

• Low-to-moderate volume

• No training to failure

• Optional short, very easy flush row (15–20 min UT2) only if recovery is good

Starting the week with lower-body strength allows maximal focus and technical quality without compromising key rowing sessions. Residual fatigue is allowed to dissipate before higher-intensity endurance work.

Tue – UT2 / Technical Row

• 45–75 min low-intensity aerobic rowing

• Emphasis on efficiency, rhythm, and stroke mechanics

Low-intensity rowing supports recovery from heavy legs while maintaining aerobic volume and reinforcing technical skill.

Wed – UT1 / Threshold Session

• Example: 3 × 10 min or 4 × 8 min at or just below threshold

• Controlled discomfort, not maximal effort

Threshold work is demanding but less neuromuscular sensitive than VO₂max intervals, making it well suited to midweek placement after lower-body lifting.

Thu – Strength (Upper + posterior chain support)

• Pulling strength, trunk stiffness, hip stability

• Lower systemic fatigue than lower-body lifting

• Keep sessions crisp and sub-maximal

Upper-focused strength maintains force production and robustness without interfering with upcoming high-intensity rowing.

Fri – UT2 (Short–Moderate)

• 40–60 min easy aerobic rowing

• Optional short pickups well below race pace

Acts as a buffer day before VO₂max or race-pace work, promoting freshness rather than accumulating fatigue.

Sat – High-Intensity Intervals (VO₂max / Race Pace)

• Example:

  • 6–8 × 500 m @ 2k pace

  • 4–6 × 750 m

  • 5 × 3 min @ VO₂max intensity

Placing intervals after several lower-fatigue days maximises power output, stroke quality, and physiological stimulus—exactly what the literature suggests is most vulnerable to interference.

Sun – Off or Very Light Recovery

• Complete rest or 20–30 min very easy movement

Allows full recovery before the next training cycle and supports long-term adaptation.

Why this tends to reduce interference:

• Heavy legs aren’t right before your most important speed sessions.

• You get recovery buffers after the biggest stressors.

• Strength volume stays supportive rather than competitive.

The “golden rules” to minimise interference and boost rowing performance

1. Don’t turn lifting into conditioning.
   If you want conditioning, do it on the erg. Keep strength training aimed at strength/power. (Rowing performance drops have been seen after high-fatigue RT in rowers.)

2. Avoid frequent training to failure.
   Especially close to key rowing sessions. It’s a fast track to performance and recovery problems.

3. Separate hard rowing from heavy legs when you can.
   Same day is possible, but spacing helps.

4. Fuel like a rower, not like a dieter.
   Low carbohydrate availability can amplify perceived fatigue and reduce quality in both modes of training (a common real-world contributor to “interference,” even when signalling pathways are discussed).

5. Periodise across the season.

• Off-season / base: build strength foundations

• Pre-competition: maintain strength, raise rowing specificity

• In-season: reduce strength volume, keep intensity, protect rowing quality

Bottom line for indoor rowing

The interference effect isn’t a reason to fear strength training—it’s a reason to programme it like a performance tool rather than a random extra workload.

For indoor rowers, the biggest mistake isn’t “mixing weights and cardio.”
It’s stacking too much fatigue, too often, and then wondering why the erg sessions go flat.

If you manage session timing, keep lifting high quality (not high carnage), and protect your key rowing workouts, you can build strength, endurance, and rowing speed together—which is exactly what the sport demands.

References:

• Hickson RC. Interference of strength development by simultaneously training for strength and endurance. (1980).

• Wilson JM et al. Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises. (2012).

• Huiberts RO et al. Concurrent Strength and Endurance Training: A Systematic Review and Meta-analysis…(2024).

• Schumann M et al. Compatibility of Concurrent Aerobic and Strength Training for Skeletal Muscle Size and Function: A Systematic Review and Meta-analysis. (2022).

• Baar K. Using Molecular Biology to Maximize Concurrent Training. (2014).

• Methenitis S. A Brief Review on Concurrent Training: From Laboratory to the Field. (2018).

• Thiele D et al. Effects of Equal Volume Heavy-Resistance Strength Training vs Strength Endurance Training in addition to rowing training in young rowers. (2020).

• Gallagher D et al. The effects of concurrent endurance and resistance training on 2000-m rowing ergometer times… (2010).

• Janicijevic D et al. Interference effects of different resistance-training protocols on rowing ergometer performance (semiprofessional rowers). (2023).