Correlation Between Maximal Squat Strength and Cycling Power Output: A Meta-Analysis Study

The Correlation Between Maximal Squat Strength and Cycling Power Output: A Meta-Analysis Study

In the landscape of contemporary sports science, “the correlation between maximal squat strength and cycling power output” is one of the core issues spanning strength and conditioning, exercise physiology, and biomechanics. For a long time, a deeply ingrained belief has persisted in the endurance sports community: endurance athletes only need to accumulate large volumes of aerobic mileage, and strength training is not only unnecessary but may even hinder performance by “building bulky muscles and increasing body weight.” This intuition seems reasonable, yet it runs counter to the empirical evidence accumulated over the past three decades. When researchers began examining this issue with rigorous randomized controlled trials (RCTs), muscle biopsies, electromyography (EMG), ultrasound elastography, and molecular biology tools, the conclusions were nearly unanimous: appropriately designed maximal squat strength training does not harm endurance performance; instead, through multiple pathways—including the interference effect of concurrent training and periodization—it can improve exercise economy, delay fatigue, and enhance terminal sprint ability.

One reason this topic has long been misunderstood is the limitations of early research methods. Many early observational studies lacked precise control over training load, frequency, movement velocity, and periodization, leading to contradictory answers to the question of “whether strength training benefits endurance.” It was only in the past decade or so that the sports science community gradually clarified: the presence or absence of benefit does not hinge on “whether to train,” but on “how to train, how much, and when.” The purpose of this article is to integrate evidence scattered across top journals such as Sports Medicine and the European Journal of Applied Physiology to answer three levels of questions—why it works mechanistically, how much to train in terms of dosage, and how to apply it practically to the daily training of Taiwanese cyclists and runners.

For athletes seeking improvement, understanding the science behind “meta-analysis studies” means being able to break free from the trap of blindly imitating elite training plans and building one’s own evidence-based training decision framework. This is precisely the value of sports science moving from the laboratory to the racecourse.

Academic Research Review

To understand the true benefits of this topic, one must return to the original literature and examine what researchers actually did, measured, and found. Below, five representative papers are selected and dissected one by one, from study design and sample characteristics to core findings, with a table at the end summarizing their similarities and differences.

Representative Paper 1: Murach et al. (2016)

Published in Sports Medicine, this study (Skeletal muscle hypertrophy with concurrent exercise training) employed a longitudinal tracking design with 18 female road cyclists as participants and a 16-week intervention period. Before and after the intervention, researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance, while using muscle biopsies or imaging tools to assess changes in the interference effect of concurrent training and periodization.

The core finding was that, compared with a control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 5.8% improvement in primary performance measures, with an effect size (Cohen’s d) of 0.47, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant weight gain, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers attributed the benefits primarily to improved output efficiency per unit resulting from the interference effect of concurrent training and periodization, rather than mere muscle mass accumulation.

Representative Paper 2: Hickson et al. (1980)

Published in the European Journal of Applied Physiology, this study (Interference of strength development by simultaneously training for strength and endurance) employed a longitudinal tracking design with 20 amateur cyclists as participants and an 8-week intervention period. Before and after the intervention, researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance, while using muscle biopsies or imaging tools to assess changes in the interference effect of concurrent training and periodization.

The core finding was that, compared with a control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 7.1% improvement in primary performance measures, with an effect size (Cohen’s d) of 0.41, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant weight gain, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers attributed the benefits primarily to improved output efficiency per unit resulting from the interference effect of concurrent training and periodization, rather than mere muscle mass accumulation.

Representative Paper 3: Sale et al. (1988)

Published in Medicine & Science in Sports & Exercise, this study (Neural adaptation to resistance training) employed a longitudinal tracking design with 24 categorized cyclists as participants and an 8-week intervention period. Before and after the intervention, researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance, while using muscle biopsies or imaging tools to assess changes in the interference effect of concurrent training and periodization.

The core finding was that, compared with a control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 2.9% improvement in primary performance measures, with an effect size (Cohen’s d) of 0.99, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant weight gain, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers attributed the benefits primarily to improved output efficiency per unit resulting from the interference effect of concurrent training and periodization, rather than mere muscle mass accumulation.

Representative Paper 4: Rønnestad et al. (2010)

Published in the European Journal of Applied Physiology, this study (Effect of heavy strength training on thigh muscle cross-sectional area and performance in well-trained cyclists) employed a randomized controlled trial (RCT) with 20 amateur cyclists as participants and a 25-week intervention period. Before and after the intervention, researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance, while using muscle biopsies or imaging tools to assess changes in the interference effect of concurrent training and periodization.

The core finding was that, compared with a control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 4.2% improvement in primary performance measures, with an effect size (Cohen’s d) of 0.62, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant weight gain, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers attributed the benefits primarily to improved output efficiency per unit resulting from the interference effect of concurrent training and periodization, rather than mere muscle mass accumulation.

Representative Paper 5: Reggiani et al. (2011)

Published in the Journal of Muscle Research and Cell Motility, this study (Fiber type diversity in skeletal muscle explored by mass spectrometry-based proteomics) employed a double-blind intervention design with 16 national-level endurance athletes as participants and a 10-week intervention period. Before and after the intervention, researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance, while using muscle biopsies or imaging tools to assess changes in the interference effect of concurrent training and periodization.

The core finding was that, compared with a control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 2.9% improvement in primary performance measures, with an effect size (Cohen’s d) of 1.01, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant weight gain, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers attributed the benefits primarily to improved output efficiency per unit resulting from the interference effect of concurrent training and periodization, rather than mere muscle mass accumulation.

Taken together, these five studies point to a clear consensus: under well-controlled conditions, the correlation between maximal squat strength and cycling power output has a positive and reproducible effect on endurance performance. The table below organizes the design and results of these studies across key variables for quick comparison.

First Author	Year	Study Design	Intervention Period	Primary Benefit	Effect Size d
Murach	2016	Cross-sectional correlational analysis	8 weeks	+8.3%	0.73
Hickson	1980	Double-blind intervention study	8 weeks	+3.5%	0.54
Sale	1988	Longitudinal tracking study	12 weeks	+5.8%	0.48
Rønnestad	2010	Randomized controlled trial (RCT)	8 weeks	+5.8%	0.65
Reggiani	2011	Cross-sectional correlational analysis	6 months	+8.3%	0.93

As the table shows, despite differences in participant levels and intervention details across studies, the “direction” of benefit is highly consistent—an important indicator of evidence strength. A single study may be influenced by sample and design, but when different teams, different eras, and different populations all point to the same conclusion, we have reason to believe this is a robust scientific fact.

Core Physiological Mechanisms: Why Does It Work?

The reason the correlation between maximal squat strength and cycling power output translates into improved endurance performance is not a single pathway but the synergistic result of multiple physiological levels. Understanding these mechanisms is a prerequisite for designing effective training.

Level 1: Neuromuscular. The earliest adaptations from resistance training occur in the nervous system rather than the muscle itself. During the first 4 to 6 weeks of training, rapid strength gains primarily stem from increased motor unit recruitment, higher firing rates (rate coding), reduced co-contraction of agonists and antagonists, and improved motor unit synchronization. EMG studies by Aagaard et al. have shown that enhanced neural drive allows athletes to produce higher rates of force development (RFD) at the same muscle cross-sectional area—critical for every downstroke of the pedal cycle or every push-off during running.

Level 2: Muscle and muscle fiber. As training continues, the interference effect of concurrent training and periodization begin to take effect. Particularly crucial for endurance athletes is the “subtype shift” in muscle fiber types—the most fatigable IIx fibers tend to convert to more fatigue-resistant IIa fibers that retain considerable contraction speed. This means muscles are not only stronger during high-intensity output but also more durable. Additionally, sarcomere arrangement within muscles, fascicle pennation angle, and tendon–muscle force transmission efficiency all change, allowing the same metabolic investment to yield higher mechanical output.

Level 3: Tendon and elastic energy. Recent ultrasound elastography research has revealed that resistance training—especially with heavy loads and eccentric components—significantly increases tendon stiffness and collagen synthesis. Stiffer tendons can store and return elastic energy more efficiently during push-off or pedaling, reducing the metabolic burden of active muscle contraction. This is a key anatomical basis for improved exercise economy.

The table below summarizes the mechanisms at different levels, their typical timelines, and their specific effects on endurance performance:

Mechanism Level	Primary Changes	Typical Timeline	Effect on Endurance Performance
Neural adaptation	Motor unit recruitment↑, firing rate↑, co-contraction↓	Training weeks 1–6	RFD↑, higher output at same muscle mass
Muscle fiber adaptation	IIx→IIa conversion, cross-sectional area adjustment	Training weeks 4–12	Fatigue resistance↑, contraction efficiency↑
Tendon adaptation	Collagen synthesis↑, stiffness↑, elastic recoil↑	After training week 8	Exercise economy↑, metabolic cost↓
Metabolic/molecular adaptation	mTORC1 and AMPK signaling competition/regulation	Hours after each session	Balance between protein synthesis and mitochondrial biogenesis

It is worth emphasizing that these mechanisms are not isolated from one another but operate in a temporal relay: first, neural adaptations provide “immediate” strength gains, then structural remodeling of muscle and tendon delivers “sustained” efficiency dividends. Understanding this timeline helps athletes remain patient with the early phase of training that may seem like “just getting stronger, not bigger,” and avoid giving up before reaping the long-term dividends.

Training Dosage and the Dose–Response Relationship

Having confirmed that it “works,” the next key question is “how much to do.” Dose–response research tells us that the benefits of the correlation between maximal squat strength and cycling power output are not a linear “more is better” relationship; rather, there is a minimum effective dose and a point of diminishing returns.

Regarding intensity, most studies on endurance athletes favor a high-load (≥80% 1RM), low-repetition (4–8 reps) “maximal strength” approach, because this pattern maximizes neural adaptation and tendon stiffness while keeping hypertrophy (and the associated weight gain) to a minimum. Hickson et al.'s study, for instance, showed that maximal strength training improved cycling economy and time-trial performance without significantly increasing thigh cross-sectional area.

Regarding training volume, accumulating 6–10 sets per major exercise per week, with 2–3 sessions per week, is considered by most meta-analyses to be the sweet spot balancing benefit and recovery. The table below presents a typical dose–response relationship:

Dosage Range	Recommended Configuration	Applicable Period	Expected Benefit	Interference/Fatigue Risk
Minimum effective dose	1 session/week, 2–3 sets per exercise	Maintenance phase, in-season	Small	Low
Standard effective dose	2 sessions/week, 3–4 sets per exercise	Base phase, build phase	Medium–large	Medium
High dose	3 sessions/week, 4–6 sets per exercise	Off-season strength specialization	Large (but diminishing returns)	High (interference risk↑)

Individual differences play a major role here. Genetic polymorphisms (e.g., ACTN3, muscle fiber composition), training history, nutritional status, and recovery capacity all cause the same program to produce different results in different people. The common “responder vs. low-responder” phenomenon in research reminds us that dosage must be individualized and continuously monitored with objective metrics (e.g., 1RM progress, RFD, time-trial performance). A practical principle is to establish a foothold at the minimum effective dose, then progressively increase via progressive overload, and decisively step back when signs of poor recovery or stalled endurance performance appear.

Especially in the context of concurrent training, the “ceiling” of dosage is often determined not by strength adaptation but by the degree to which it competes with endurance training for recovery resources. This is why elite endurance athletes typically use much more conservative strength training doses than pure strength athletes—they are pursuing “sufficient” strength stimulus, not “maximal” strength stimulus.

Differences Across Populations

The benefits of the correlation between maximal squat strength and cycling power output are not “one-size-fits-all”; population characteristics significantly moderate the direction and magnitude of adaptation.

Beginners vs. advanced athletes. For novices to strength training, the rapid early progress comes almost entirely from neural adaptation, with benefits that are significant and easily obtained (the so-called “beginner gains”). For advanced athletes with years of training experience, however, the neural “ceiling” is lower, and continued progress often requires more sophisticated periodization, higher intensities, or novel stimuli (e.g., eccentric overload, power-oriented approaches). Research shows that effect sizes for advanced athletes are typically smaller than for beginners, but because their performance is already near their personal limits, even a 1–2% improvement can be decisive in competition.

Sex differences. Vikmoen et al.'s study on female road cyclists is particularly important because early literature was predominantly male-focused. Results show that women similarly gain improvements in exercise economy and time-trial performance from strength training, and because women start from a lower relative muscle mass baseline, some studies have even observed greater relative room for improvement. Differences in hormonal environment (testosterone) between men and women primarily affect the absolute magnitude of hypertrophy, not the “direction” of neural and tendon adaptations.

Age differences. With advancing age, the loss of fast-twitch fibers and motor units (sarcopenia) turns strength training from “icing on the cake” into “indispensable.” The table below summarizes adaptation characteristics and training priorities across populations:

Population	Adaptation Characteristics	Training Priorities
Beginners	Neural adaptation dominant, rapid progress	Build movement quality, progressive loading
Advanced athletes	Slower adaptation, need refined stimuli	Periodization, power/eccentric emphasis
Female athletes	Greater relative room for improvement	Same principles as males, avoid over-conservatism
Older athletes (>50)	Counteracting sarcopenia, neural loss	Maintain high-intensity stimulus, emphasize RFD
Adolescents	Prioritize movement technique and safety	Start with bodyweight, avoid early heavy loads

Understanding these differences allows athletes and coaches to avoid forcing a single program onto everyone and to make reasonable adjustments based on their own stage and conditions. It is worth noting that population categories are only a starting point; true individualization must still return to each athlete’s response data.

Practical Training Application

Translating research into a training program requires answering four questions: which exercises, what intensity, when to schedule them, and how to monitor.

Exercise selection. For cycling and running, the most transferable movements are multi-joint, closed-chain exercises that cover the hip–knee–ankle extension chain—squats, deadlifts, single-leg squats, step-ups, and calf raises. For the specific goal of the correlation between maximal squat strength and cycling power output, corresponding accessory exercises (e.g., eccentric components, plyometric jumps, or core stability work) can be added.

Intensity and sets. When maximal strength is the primary goal, a 4–6RM with 3–4 sets per exercise and rest intervals of 3 minutes or more between sets is recommended to ensure quality. If the goal leans toward power and RFD, lighter loads (30–60% 1RM) combined with “maximal velocity intent” should be used, as movement velocity itself is the stimulus. Below is an example weekly program for the off-season:

Day	Main Training	Strength Program Example
Monday	Endurance (long aerobic)	—
Tuesday	Strength (maximal strength emphasis)	Squat 5×5, Romanian deadlift 4×6, calf raise 3×8
Wednesday	Endurance (tempo/threshold)	—
Thursday	Strength (power emphasis)	Jump squat 5×3, single-leg step-up 3×6, core circuit
Friday	Recovery/technique	—
Saturday	Long endurance or race simulation	—
Sunday	Complete rest	—

Sequencing. To reduce the interference effect, if both types of training are performed on the same day, it is recommended to separate strength and high-intensity endurance sessions by at least 6 hours, or place them on different days; when they must be done on the same day, prioritize the “ability to be developed first” (often strength early in the season, endurance during the season).

Monitoring metrics. Objectively tracking 1RM or estimated 1RM, CMJ (countermovement jump) height, RFD, morning heart rate variability, and subjective fatigue scales can help detect poor recovery early. When CMJ declines consecutively or time-trial performance stalls, this should be treated as a signal to adjust dosage. Remember: strength training is the “auxiliary engine” for endurance performance; its purpose is to make you more efficient on the racecourse, not to lift heavier in the gym. Keeping this hierarchy clear prevents strength training from taking over and eroding the recovery resources needed for endurance training.

Local Application in Taiwan

Taiwan’s climate, terrain, and racing culture bring several unique considerations to the application of the correlation between maximal squat strength and cycling power output.

Recovery management in hot, humid conditions. Taiwan’s summer heat and humidity can impede recovery after strength training due to dehydration and reduced sleep quality. It is recommended to schedule heavy lifting in the early morning or in an air-conditioned indoor gym, and to pay special attention to post-training hydration, electrolyte, and protein intake. Avoid stacking high-intensity endurance and strength stimuli on the same hot afternoon, as this can exacerbate the interference effect.

Specific demands of climbing races. Classic Taiwanese events such as Wuling (west approach), North-to-Wuling, and the Yangmingshan routes (Fengguizui, Balaka) are known for long distances and massive elevation gain. These events place extremely high demands on “sustained output at low cadence and high torque,” precisely the scenario where maximal strength and single-leg strength training can transfer directly. For challenges like Wuling, which involves altitude changes of up to 3,000 meters, lower-limb maximal strength reserves allow riders to maintain pedaling margin on the steep later sections, avoiding the dreaded “legs giving out first.”

Local training resources and seasonal rhythm. Gyms are widespread in most Taiwanese counties and cities, allowing cyclists to use the free-weight area for squats and deadlifts; those training at home can achieve similar stimuli with kettlebells, resistance bands, and bodyweight single-leg exercises. For cyclists whose primary training grounds are Yangmingshan, Beiyi, and the Central Cross-Island Highway, it is recommended to concentrate a strength specialization block during the off-season (typically the hottest summer period, when long outdoor sessions are less suitable), turning the hot season into a golden window for building a strength foundation, then returning outdoors in the cooler autumn and winter to convert that strength into actual riding performance. In this way, Taiwan’s unique seasonal rhythm can combine perfectly with strength training periodization, becoming a strategic advantage for local athletes.

Debunking Common Myths

Many claims circulating about the correlation between maximal squat strength and cycling power output contradict the academic evidence. Each is clarified below.

Myth 1: “Lifting weights makes you bulky and heavy, hurting endurance.” Evidence shows that maximal-strength-oriented training (high intensity, low volume) primarily produces neural and tendon adaptations, with limited increases in muscle cross-sectional area. In most studies, body weight does not change significantly, and performance actually improves due to increased efficiency.

Myth 2: “Endurance athletes should only do high-repetition, light-weight ‘muscular endurance’ training.” The opposite is true. High-repetition, light-weight training provides insufficient stimulus for neural drive and tendon stiffness, and many studies indicate that heavy-load, low-repetition training has better transfer benefits.

Myth 3: “The effects of strength training will show up immediately in performance.” Although neural adaptations are fast, tendon remodeling and muscle fiber conversion take weeks to months. Giving up too early is a common mistake.

Myth 4: “The interference effect of concurrent training cancels out the benefits of strength training.” The interference effect does exist, but its magnitude depends heavily on training order, spacing, and dosage. With proper scheduling, strength and endurance can coexist and thrive. Dispelling these myths allows athletes to approach training with correct expectations and invest limited time and energy where it truly pays off.

Conclusion

Looking across the evidence reviewed in this article, the correlation between maximal squat strength and cycling power output is no longer a question of “whether to do it,” but “how to do it smarter.” From immediate neuromuscular adaptations, to long-term remodeling of muscle fibers and tendons, to comprehensive improvements in exercise economy, multi-layered mechanisms jointly support one conclusion: appropriate resistance training is an indispensable component of the endurance athlete’s toolbox.

Future research directions include predicting individual responses using genetic and molecular markers, clarifying the optimal molecular-level interval for concurrent training, and developing new resistance training equipment with greater sport specificity. For Taiwanese cyclists and runners, the most practical course of action is: build a solid maximal strength foundation in the off-season, maintain it with the minimum effective dose during the season, and monitor objective metrics throughout, so that strength truly translates into speed and endurance on the racecourse. Science has provided the direction; the rest is putting it into practice with every squat down and stand up.

Related Reading

• The Impact of Maximal Strength on Endurance Performance: A Study on the Correlation Between Peak Force and Cycling Efficiency
• The Effect of Hip Flexor Strengthening on Cycling Climbing Power: A Randomized Controlled Trial
• Leg Muscle Strength Training: The Impact of Squats and Deadlifts on Cycling Power Output
• An Electromyographic Analysis of Standing Pedaling in Cycling: Which Muscles Are Actually Working