Strength training for endurance athletes: does it work?

The short answer

Yes. Strength training improves performance in most runners, cyclists and triathletes. A 2014 review of trained runners and cyclists found better exercise economy, maximal speed, rate of force development and endurance performance, with no gain in body mass, loss of VO2max, or harm to capillaries or aerobic enzymes.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}

A systematic review the same year, covering 26 studies, reached the same conclusion for economy, power and performance.^{2Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 27.},^{3Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 29.}

Many endurance athletes still skip it. Among runners at the 2008 U.S. Olympic Marathon Trials, nearly half did no strength training at all.^{4Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 6.}

What strength training does for runners, cyclists and triathletes

Lifting does little for aerobic capacity itself. In trained athletes it has only a trivial effect on VO2max.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.} The benefits come from changes in the muscles and how athletes use them:

• Economy is the oxygen required to hold a given pace or power. Several studies found improved running economy after 8–14 weeks of heavy lifting, or 6–12 weeks of explosive work, while control groups didn’t change.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.} The likely reason is that each stride or pedal stroke becomes a smaller share of the athlete’s maximum, so fewer of the less efficient fast-twitch fibers are needed.^{6Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 4.}
• Runners store and return elastic energy with each stride. Both heavy and explosive lifting can stiffen the muscle-tendon system, which is associated with better running economy. Cycling involves little of this elastic rebound, so the effect matters less there.^{7Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 5.}
• Heavy lifting can raise top speed or power at VO2max and extend the time an athlete can hold it.^{8Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 3.} In one study, cyclists who lifted produced 7% more power in a 5-minute all-out effort after 3 hours of riding. Cyclists who only rode didn’t improve.^{8Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 3.}
• In trained athletes, lifting has improved 3 km and 5 km running times and 5-minute and 45-minute cycling time trials.^{9Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 9.}
• Jack Daniels encourages all runners to lift. He suggests its biggest benefit may be resistance to injury, which lets runners train harder.^{10Daniels, Daniels’ Running Formula, 4th ed., p. 194.} The NSCA also lists overuse injury prevention and fewer muscle imbalances among the benefits.^{11Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 588.} These injury claims are expert opinion; none of the reviews here measured injury rates.

The evidence for triathletes is thinner. In the systematic review, one triathlon study improved running speed at VO2max and another found no change on the bike. Only one of three improved running economy.^{12Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 10.} For the swim, conventional gym exercises have shown little or no effect. The successful studies used swim-specific movements.^{13Dallam, in USA Triathlon, Complete Triathlon Guide, p. 53.}

Heavy, explosive or high-rep strength training: which is best?

The studies distinguish three types of strength work:

Type	What it looks like	What the evidence shows
Heavy	Loads you can lift for 1–15 reps14Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 1.	Improves running economy and performance. The best-supported choice for cycling14Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 1.,15Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 7.
Explosive	0–60% of 1RM (including body weight), moved as fast as possible14Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 1.	Improves running economy and performance. Weak results for cycling14Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 1.,8Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 3.
High-rep	Light loads for many reps	Weakest case in trained athletes (see below)

Where heavy and explosive work have been compared directly in runners, heavy training has tended to come out ahead.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.} Lift with the intent to move the weight as fast as possible. Even when the bar moves slowly, that intent appears to drive gains in rate of force development.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}

Sources disagree about light, high-rep work. The traditional approach for endurance athletes uses relatively light loads and long sets, aiming to train the slow, fatigue-resistant fibers.^{16Zatsiorsky, Kraemer and Fry, Science and Practice of Strength Training, 3rd ed., p. 244.} The same textbook notes, though, that in untrained people higher-rep loads (20–28RM) built less strength than heavier ones,^{16Zatsiorsky, Kraemer and Fry, Science and Practice of Strength Training, 3rd ed., p. 244.} and that skaters and skiers who went from 30–50 one-leg squats to several hundred saw no real improvement in their sport.^{16Zatsiorsky, Kraemer and Fry, Science and Practice of Strength Training, 3rd ed., p. 244.} In cycling, the studies that found no performance benefit tended to use low-load explosive work, low volumes or short programs.^{6Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 4.}

Light work can help less experienced athletes. In recreational runners, muscular-endurance, explosive and heavy programs all improved treadmill running.^{11Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 588.} The NSCA’s sample in-season program for a beginner high school cross-country runner uses loads under 67% of 1RM for more than 12 reps.^{17Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 465.},^{18Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 475.} For novices, a broad range of strength programs can help. For trained athletes, heavy lifting has the strongest evidence.

Strength level matters too. For weak or untrained endurance athletes, a general maximal-strength program may be the most efficient start. Athletes who are already strong may need more explosive and reactive work to keep improving.^{3Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 29.}

Will lifting make endurance athletes bulky or slow?

Rarely, with programs like those studied. Across 8–16 weeks of added lifting, cyclists, runners, triathletes and cross-country skiers didn’t gain total body mass, and their VO2max development wasn’t harmed. The target muscles grew only slightly, by about 3–6%.^{7Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 5.} Heavy endurance volume itself blunts muscle growth.^{7Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 5.}

The review that covered these studies found no reports of strength training harming endurance performance. It does note that not every study found a benefit, especially in men.^{8Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 3.}

What is the interference effect in concurrent training?

Combining endurance and strength training can blunt strength and power gains, mainly when the endurance training is high in intensity, volume or frequency. Most studies show heavy lifting doesn’t hurt aerobic power.^{19Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 121.} Power suffers more than slow strength. In one study, squat reps dropped by 13–36% when lifting came 30 minutes after a 25-minute aerobic session.^{20Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 123.} One strength textbook adds that the closer together the two types of session are, the more they interfere. Same-day training interferes more than alternate days.^{21Zatsiorsky, Kraemer and Fry, Science and Practice of Strength Training, 3rd ed., p. 245.}

That matters less than it sounds. Endurance athletes lift to run or ride better, not to get as strong or as big as possible, and the endurance gains held up in the research above. The molecular science behind interference is still early.^{22Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 28.} One coach who specializes in hybrid training argues that, in practice, most of the problem comes down to eating enough and recovering before the next session.^{23Viada, The Ultimate Hybrid Athlete, p. 85.}

How often should endurance athletes lift, and how much?

For trained endurance athletes, the review’s practical recommendations are:^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}

• During the build phase, lift twice a week for about 12 weeks, mixing heavier and lighter days.
• Use 4–10 reps for 2–3 sets, with about 2–3 minutes’ rest.
• Choose exercises for the muscles and movement patterns of the sport. Multi-joint exercises such as squats, deadlifts and their single-leg versions are thought to transfer better than machine isolation work.^{2Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 27.}
• Learn the lifts with light loads before going heavy.

One study replaced some endurance work with a single explosive session a week and found no change in running economy. Programs that improved it used 2–3 sessions a week.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.} Duration also matters: a 6-week cycling study found no benefit.^{8Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 3.} Most studies ran for about 10 weeks.^{24Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 26.}

Several cycling studies used this 12-week heavy block, with two sessions a week of half squats, single-leg leg press, hip flexion and toe raises:^{25Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 15.}

Weeks	Session 1	Session 2
1–3	10RM	6RM
4–6	8RM	5RM
7–12	6RM	4RM

How to combine strength and endurance training

How to adjust lifting through the season

Phase	Aim	Lifting sessions per week
Just after the race season	Learn technique, build strength while endurance load is low	21Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.
Preparation	Keep building maximal strength	21Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.
Competition season	Hold on to what was built	About 1, heavy and low volume1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.

The NSCA’s general guideline for trained athletes in season is 1–3 sessions a week. It also advises fewer sessions when endurance training volume is already high.^{26Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 464.}

Don’t drop lifting entirely in season. Strength fades faster than it’s built, so lifting only in the off-season tends to leave athletes no stronger year to year.^{27Dallam, in USA Triathlon, Complete Triathlon Guide, p. 58.} For maintenance, keep the athlete’s usual weight and sets, reducing frequency if needed.^{27Dallam, in USA Triathlon, Complete Triathlon Guide, p. 58.} In one cycling study, a 23% gain in half-squat strength after 12 weeks was still there at week 25.^{28Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 19.} The in-season sessions in that study were just 2 sets of 5 half squats and leg presses, plus 1 set of 6 hip flexion and calf raises.^{25Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 15.}

How to schedule lifting during the week

• Expect heavy, sore legs in the first days after the initial sessions. Keep endurance training light for the first 2–3 weeks.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}
• On days with both types of training, lift after endurance work. One triathlon coach finds that endurance work hurts lifting less than lifting hurts endurance work. He acknowledges that the best order hasn’t been established.^{29Dallam, in USA Triathlon, Complete Triathlon Guide, p. 59.}
• After a threshold run, one hybrid coach suggests 6–8 hours and a full meal before lifting. After an easy run of under an hour, 4–6 hours may be enough.^{30Viada, The Ultimate Hybrid Athlete, p. 208.}
• Daniels suggests about 4 weeks at one level of resistance training before increasing it.^{31Daniels, Daniels’ Running Formula, 4th ed., p. 197.}
• Triathletes short on time can add strength work to the end of an easy run or swim.^{32USA Triathlon, Complete Triathlon Guide, p. 105.}

A sample strength and running schedule

This illustrative week for a runner’s build phase follows the principles above. It is not a tested protocol:

Day	Endurance	Strength
Mon	Rest or easy	None
Tue	Intervals or threshold run (morning)	Heavier session, 6–8 hours later: 2–3 × 4–6
Wed	Easy run	None
Thu	Easy run	Lighter session after the run: 2–3 × 8–10
Fri	Rest or easy	None
Sat	Long run	None
Sun	Easy run	None

For a cyclist or triathlete, swap in the key bike or brick session on Tuesday. In season, drop Thursday’s session and keep one short, heavy one.

What the evidence does and doesn’t say

The evidence favors lifting, but most studies were small. The two main reviews are from 2014. Most of the trials they cover had fewer than ten athletes in the strength group.^{33Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 11.},^{34Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 13.} Most interventions lasted 8–12 weeks, so long-term effects are less certain.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.},^{24Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 26.} The systematic review included only trained athletes: at least six months of training, six or more hours a week, or a VO2max of at least 50 ml/kg/min.^{35Beattie et al., The Effect of Strength Training on Performance in Endurance Athletes, p. 7.} That makes the findings relevant to serious amateurs.

Coaching a client through it

1. Take new clients through your normal pre-participation screening before loading up.
2. Schedule lifting around the key sessions set by the client’s endurance coach or plan.
3. Teach technique with light loads, then move to heavy sets of 4–10.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}
4. Start after the race season if you can, when endurance training is lighter.^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.}
5. Stop sets short of failure. In one triathlon coach’s view, controlled sets beat failure sets because they cause less pain and fatigue.^{36Dallam, in USA Triathlon, Complete Triathlon Guide, p. 60.}
6. Keep one session in season to maintain strength until race day.

Common questions

Does strength training increase VO2max?

Not meaningfully in trained athletes. The benefits come from economy, power and fatigue resistance.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.}

Are bodyweight circuits or plyometrics enough?

For runners, explosive and plyometric work can improve economy and performance.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.} For cyclists, heavy lifting has much stronger support.^{15Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 7.} Very light, high-rep work has the weakest case for trained athletes.^{16Zatsiorsky, Kraemer and Fry, Science and Practice of Strength Training, 3rd ed., p. 244.}

How long does strength training take to improve endurance?

Running economy has improved after 6–14 weeks, depending on the type of training.^{5Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 2.} Expect at least a couple of months of consistent work.

Should endurance athletes lift during race week?

The sources here don’t give a race-week rule. They support keeping a low-volume maintenance session through the season,^{1Rønnestad and Mujika, Optimizing strength training for running and cycling endurance performance: A review, p. 6.} and scheduling it so it doesn’t affect competition days.^{17Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 465.}