Strength Training for Endurance Athletes: How Much Is Enough?

Introduction

Endurance athletes often have a complicated relationship with strength training.

Some believe lifting weights will make them too bulky. Others add three or four gym sessions to an already demanding swim, bike, and run schedule, only to wonder why they're constantly tired.

The reality sits somewhere in between. Strength training for endurance athletes can improve performance, durability, and resilience, but more isn't necessarily better.

The goal isn't to become a powerlifter. The goal is to become a stronger endurance athlete without creating so much fatigue that it compromises the training that matters most.

Why Do Endurance Athletes Need Strength Training?

Swimming, cycling, and running are primarily endurance activities, but that doesn't mean strength is irrelevant.

Every stride, pedal stroke, and swimming pull requires the muscles to produce force.

For runners, greater strength can improve running economy and the ability to maintain performance as fatigue accumulates. For cyclists, strength can support force production and sprinting ability. For swimmers, strength contributes to propulsion, body position, and the ability to maintain technique as fatigue develops.

Research published in 2025 found that adding strength training can improve several determinants of endurance performance, although the results aren't identical across every athlete or training method. 

This is an important distinction. Strength training isn't a replacement for endurance training. It's an addition that can make the endurance training more effective.

How Much Strength Training Is Enough?

For most endurance athletes, “two sessions per week” is a very effective starting point.

You don't need to spend 90 minutes in the gym. You don't need six exercises for every muscle group. And you certainly don't need to finish every session unable to walk down the stairs.

A well-designed session might take “30–45 minutes” and focus on a handful of major movements.

The exact prescription should change according to your training age, race goals, current workload, and recovery capacity.

If you're still building your overall training week, our guide to How to Train for Your First Sprint Triathlon explains how to balance swimming, cycling, running, strength, and recovery without overcomplicating your program

One Session or Two?

This is where things become individual.

If you're a beginner, one strength session per week can be enough to establish the habit and begin building general strength. If you're already experienced with resistance training, two sessions per week may provide a stronger stimulus.

For a triathlete training across three sports, however, the question isn't simply: 

"How much strength can I do?" 

It's: 

"How much strength can I recover from while still performing my key swim, bike and run sessions?"

That's a much better question. A triathlete swimming four times, cycling three times, and running three times each week has a very different recovery budget than someone training for their first sprint triathlon.

SLS3's beginner triathlon guidance recommends one strength or mobility session within a typical three-to-five-session weekly program, reinforcing the idea that strength should complement rather than overwhelm the endurance workload.

What Should an Endurance Athlete Actually Do in the Gym?

This is where many athletes get it wrong. You don't need a bodybuilding program. You need movements that develop useful strength while keeping fatigue manageable.

A simple full-body session might include:

Lower body

• Squat or split squat

• Romanian deadlift or hip hinge

• Step-up or lunge

Upper body

• Pull-up or lat pulldown

• Row

• Push-up or press

Core and stability

• Pallof press

• Loaded carry

• Plank variation

You can also include explosive movements such as jumps or medicine-ball exercises when appropriate.

The goal is “quality rather than quantity”.

For experienced athletes, heavier resistance with relatively low repetition volumes can be particularly useful. USA Triathlon's current guidance for triathletes recommends two 30–45-minute sessions per week using relatively high intensities and low-to-moderate repetition ranges.

Do Endurance Athletes Need to Lift Heavy?

Not always, but don't be afraid of heavier weights.

One of the biggest misconceptions surrounding strength training for endurance athletes is that you need to perform endless sets of 15–20 repetitions with light weights.

That's not necessarily the best approach. If the goal is to build strength, the resistance needs to be challenging enough to drive meaningful adaptation.

For an experienced athlete, that might mean relatively heavy loads and fewer repetitions. For a beginner, however, the priority should be learning the movement correctly and gradually increasing resistance.

Strength training should be progressive. You don't need to chase maximum lifts, but you should give your body a reason to become stronger.

Will Strength Training Make Endurance Athletes Bulky?

This is one of the most persistent myths in endurance sport. Adding sensible resistance training doesn't automatically mean you'll gain significant muscle mass.

Muscle growth depends on training volume, intensity, nutrition, energy availability, genetics, and the overall training program. An endurance athlete performing two focused strength sessions per week isn't suddenly going to turn into a bodybuilder.

In fact, for many athletes, the goal is the opposite. Improve strength without adding unnecessary body mass.

This is particularly relevant for runners and triathletes, where relative strength (how much force you can produce relative to body mass) can be more useful than simply becoming heavier.

When Should You Strength Train?

Scheduling matters. The biggest mistake isn't necessarily doing too much strength training. It's putting the strength session in the wrong place.

If you perform a demanding leg session the day before your most important run workout, don't be surprised when the run suffers.

The same principle applies to cycling intervals and key swim sessions. When possible, place strength training so that it doesn't compromise your highest-priority endurance sessions.

If strength and endurance training need to occur on the same day, the order can also matter depending on your goal. Research into concurrent training suggests that separating sessions where practical can help manage interference and fatigue, particularly when strength or power development is a priority.

For most triathletes, I'd rather see: 

Key endurance session → recovery → strength

than:

Hard strength session → hard endurance session → another hard session

The objective is to manage the total stress.

Strength Training During Heavy Endurance Blocks

This is where experienced athletes need to be smart. When your endurance volume increases, you don't necessarily need to increase your strength volume alongside it.

In fact, the opposite may be appropriate. During a high-volume training block, reduce sets and exercises while keeping intensity high enough to preserve strength.

Think maintenance rather than development. You might normally perform two strength sessions each week. During your biggest endurance weeks, one shorter session may be enough. That's not losing fitness. It's managing fatigue.

When overall training load is high, recovery becomes even more important. Alongside sleep, nutrition, and sensible load management, athletes may also use recovery tools such as SLS3 Compression Recovery Boots as part of their post-training routine.

What About Strength Training Before a Race?

As competition approaches, the goal changes again. You're no longer trying to build large amounts of new strength. You're trying to arrive at the start line “strong, fresh and ready to perform”.

That means reducing strength volume during the final weeks while maintaining some exposure to the movements and loads you've been using throughout the program.

Avoid introducing new exercises, huge lifting sessions, or unfamiliar movements immediately before a race.

The same principle applies to endurance training. The closer you get to race day, the more valuable freshness becomes.

Strength Training and Injury Prevention

It's tempting to describe strength training as an injury-prevention guarantee. It isn't. No training method can eliminate injury risk.

But stronger muscles, tendons, and supporting structures can improve an athlete's ability to tolerate training loads.

Strength work can also address weaknesses or movement limitations that may become more apparent as training volume increases.

USA Triathlon highlights strength and conditioning as a way to support coordination, muscular endurance, body composition and resilience while complementing the predominantly aerobic demands of triathlon.

The important word is “complementing”. Strength training should help you handle your endurance training better.

For athletes who spend long periods running, cycling, or training on their feet, compression ankle sleeves can also provide a simple option for everyday support.

The Biggest Mistake: Doing Too Much

This is the part I would emphasize most. I've seen endurance athletes become so excited about strength training that they turn it into another endurance sport.

Five gym sessions. Hundreds of repetitions. Constant muscle soreness. And suddenly the athlete's bike performance drops, their running legs feel heavy, and their recovery deteriorates.

That's not successful concurrent training. More training isn't automatically better training. For an endurance athlete, the gym supports the bigger picture. You should walk out feeling that you've provided your body with a useful stimulus, not that you've destroyed yourself.

That same principle applies to your endurance sessions. Our guide to Zone 1 Training for Triathletes explains why easy training is an important part of absorbing harder work and managing overall fatigue.

A Simple Strength Training Template for Endurance Athletes

If you're unsure where to start, keep it simple.

30–45 minute session

1. Squat or split squat

2–3 sets × 4–8 repetitions

2. Romanian deadlift or hip hinge

2–3 sets × 4–8 repetitions

3. Pull-up or row

2–3 sets × 5–10 repetitions

4. Press or push-up

2–3 sets × 5–10 repetitions

5. Loaded carry or core exercise

2–3 sets

Rest enough between sets to maintain good technique and quality. You don't need to leave the gym exhausted. You need to leave the gym stronger over time.

The Bottom Line

Strength training for endurance athletes doesn't need to be complicated.

For most triathletes and endurance athletes, one or two focused sessions per week are enough to provide meaningful benefits without overwhelming the rest of the training program.

• Focus on major movements.

• Use progressive resistance.

• Keep the sessions relatively short.

• Schedule them intelligently.

• And adjust the volume when endurance training becomes harder.

The best strength program isn't the one that leaves you the most sore. It's the one that makes you stronger, more durable, and better able to handle your endurance training.

Remember: you're not training to become a weightlifter. You're lifting weights so you can become a better endurance athlete.

References

1. Ramos-Campo DJ et al. The Effect of Strength Training on Endurance Performance Determinants in Middle- and Long-Distance Endurance Athletes: An Umbrella Review of Systematic Reviews and Meta-Analysis. Journal of Strength and Conditioning Research, 2025.

2. Huiberts RO et al. Concurrent Strength and Endurance Training: A Systematic Review and Meta-Analysis on the Impact of Sex and Training Status. Sports Medicine, 2024.

3. Zhang F et al. The effects, mechanisms, and influencing factors of concurrent strength and endurance training with different sequences. Frontiers in Sports and Active Living, 2025.

4. USA Triathlon. Strength Training for Triathletes: Why It's Non-Negotiable.