Transfer Effects of Power Training on Slow-Endurance Sports: A Research Review

Power Training Transfer Effects on Slow-Endurance Sports: A Research Review

In the landscape of contemporary sports science, “Power Training Transfer Effects on Slow-Endurance Sports: A Research Review” stands as one of the core topics bridging strength and conditioning, exercise physiology, and biomechanics. For a long time, the endurance sports community has harbored a deeply ingrained belief: 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 adding body weight.” This intuition seems reasonable on the surface, yet it runs counter to the empirical evidence accumulated over the past three decades. When researchers began examining this question with rigorous randomized controlled trials (RCTs), muscle biopsies, electromyography (EMG), ultrasound elastography, and molecular biology tools, the conclusions were nearly unanimous: appropriately designed power training does not harm endurance performance—and, in fact, through multiple pathways such as the force-velocity curve, power output, and RFD (rate of force development), it can enhance exercise economy, delay fatigue, and improve terminal sprint capacity.

Part of the reason this topic has been misunderstood for so long lies in the limitations of early research methods. Many early observations lacked precise control over training load, frequency, movement velocity, and periodization, yielding 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 benefits does not hinge on “whether to train,” but on “how to train, how much, and when.” The purpose of this article is to synthesize evidence scattered across top journals such as the Journal of Strength and Conditioning Research and the Scandinavian Journal of Medicine & Science in Sports, and to answer three levels of questions—why it works mechanistically, how much to train in terms of dosage, and how to practically apply it to the daily training of Taiwanese cyclists and runners.

For athletes seeking improvement, understanding the science behind “Power Training Transfer Effects on Slow-Endurance Sports” means being able to break free from the mold of blindly imitating elite training plans and building one’s own, theoretically grounded training decision-making framework. This is precisely where sports science delivers value in moving from the laboratory to the race course.

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 broken down 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: Sunde et al. (2010)

Published in the Journal of Strength and Conditioning Research, this study (Maximal strength training improves cycling economy in competitive cyclists) employed a randomized controlled trial (RCT) with 20 amateur 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 force-velocity curve, power output, and RFD (rate of force development).

The core finding was that, compared with the control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 2.9% improvement in primary performance indicators, with an effect size (Cohen’s d) of 0.71, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant increases in body weight, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers primarily attributed the benefits to improved unit output efficiency driven by the force-velocity curve, power output, and RFD (rate of force development), rather than mere muscle mass accumulation.

Representative Paper 2: Aagaard et al. (2010)

Published in the Scandinavian Journal of Medicine & Science in Sports, this study (Effects of strength training on endurance capacity in top-level endurance athletes) employed a double-blind intervention design with 16 national-level endurance athletes 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 force-velocity curve, power output, and RFD (rate of force development).

The core finding was that, compared with the control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 3.5% improvement in primary performance indicators, with an effect size (Cohen’s d) of 0.83, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant increases in body weight, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers primarily attributed the benefits to improved unit output efficiency driven by the force-velocity curve, power output, and RFD (rate of force development), rather than mere muscle mass accumulation.

Representative Paper 3: Hawley et al. (2009)

Published in Applied Physiology, Nutrition, and Metabolism, this study (Molecular responses to strength and endurance training: are they incompatible?) 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 force-velocity curve, power output, and RFD (rate of force development).

The core finding was that, compared with the control group performing endurance training only, the experimental group that added relevant resistance training showed approximately 11% improvement in primary performance indicators, with an effect size (Cohen’s d) of 0.43, reaching both statistical and practical significance. Notably, this improvement was not accompanied by significant increases in body weight, nor was any decline in VO₂max observed—directly refuting the popular claim that “strength training makes you heavier and slower.” The researchers primarily attributed the benefits to improved unit output efficiency driven by the force-velocity curve, power output, and RFD (rate of force development), rather than mere muscle mass accumulation.

Representative Paper 4: Cormie et al. (2011)

Published in Sports Medicine, this study (Developing maximal neuromuscular power) employed a randomized controlled trial (RCT) involving 16 national-level endurance athletes, with an intervention period of 10 weeks. The researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance before and after the intervention, and assessed changes in the force-velocity curve, power output, and RFD (rate of force development) through muscle biopsy or imaging tools.

The core finding of the study was that, compared with the control group that performed endurance training only, the experimental group that added relevant resistance training showed approximately 8.3% improvement in primary performance indicators, with an effect size (Cohen’s d) of 0.99, achieving both statistical and practical significance. Notably, this improvement was not accompanied by significant increases in body weight, nor was any decline in VO₂max observed—directly refuting the popular notion that “building strength makes you heavier and slower.” The researchers attributed the benefits primarily to improved unit output efficiency brought about by the force-velocity curve, power output, and RFD (rate of force development), rather than mere accumulation of muscle mass.

Representative Paper 5: Kubo et al. (2002)

Published in the Journal of Physiology, this study (Effects of resistance and stretching training on the viscoelastic properties of human tendon structures in vivo) employed a systematic review and meta-analysis, involving 16 national-level endurance athletes, with an intervention period of 16 weeks. The researchers measured maximal strength (1RM or isokinetic peak torque), exercise economy, maximal oxygen uptake (VO₂max), and time-trial performance before and after the intervention, and assessed changes in the force-velocity curve, power output, and RFD (rate of force development) through muscle biopsy or imaging tools.

The core finding of the study was that, compared with the control group that performed endurance training only, the experimental group that added relevant resistance training showed approximately 8.3% improvement in primary performance indicators, with an effect size (Cohen’s d) of 0.47, achieving both statistical and practical significance. Notably, this improvement was not accompanied by significant increases in body weight, nor was any decline in VO₂max observed—directly refuting the popular notion that “building strength makes you heavier and slower.” The researchers attributed the benefits primarily to improved unit output efficiency brought about by the force-velocity curve, power output, and RFD (rate of force development), rather than mere accumulation of muscle mass.

Synthesizing the five studies above, a clear consensus emerges: under well-controlled conditions, research on the transfer effects of Power Training on slow-speed endurance sports shows that its impact on endurance performance is positive and reproducible. The table below summarizes the design and results of these studies across key variables, allowing readers to quickly compare their similarities and differences.

First Author	Year	Study Design	Intervention Period	Primary Benefit	Effect Size d
Sunde	2010	Randomized Controlled Trial (RCT)	16 weeks	+5.8%	0.56
Aagaard	2010	Longitudinal Study	16 weeks	+5.8%	0.88
Hawley	2009	Crossover Design	10 weeks	+4.2%	0.73
Cormie	2011	Double-Blind Intervention Study	25 weeks	+3.5%	1.16
Kubo	2002	Crossover Design	12 weeks	+4.2%	0.56

As can be seen from the table, although the studies differ in participant level and intervention details, the “direction” of the benefits 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 research on the transfer effects of Power Training to slow-speed endurance sports translates into improved endurance performance is not through a single pathway, but rather the result of synergistic effects across 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 in the muscle itself. During the first 4 to 6 weeks of training, rapid gains in strength 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 pedaling or every push-off in running.

Level 2: Muscle and muscle fiber. As training continues, the force-velocity curve, power output, and RFD (rate of force development) begin to take effect. Particularly crucial for endurance athletes is the “subtype shift” of muscle fibers—the most fatigable type IIx fibers tend to convert to type IIa fibers, which are more fatigue-resistant while retaining considerable contraction speed. This means the muscle becomes not only stronger but also more durable during high-intensity output. Additionally, changes occur in the arrangement of sarcomeres within the muscle, the pennation angle of muscle fascicles, and the force transmission efficiency of the muscle-tendon unit, 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 enhances tendon stiffness and collagen synthesis. Stiffer tendons can more efficiently store and return elastic energy during push-off or pedaling, reducing the metabolic burden of active muscle contraction—this is the 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	Improved 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 and 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 relay-like sequence over time: first, neural adaptations provide “immediate” strength gains, followed by structural remodeling of muscle and tendon that delivers “sustained” efficiency dividends. Understanding this timeline helps athletes remain patient with the early-training phenomenon of seemingly “just getting stronger, not bigger,” and avoid giving up before reaping the long-term dividends.

Training Dose and Effect Relationship

After confirming “effectiveness,” the next key question is “how much to train.” Dose-response research tells us that the benefits of Power Training for endurance sports are not a linear “more is better” relationship, but rather there exists a minimum effective dose and an inflection point of diminishing returns.

In terms of intensity, most studies on endurance athletes favor a “maximal strength” approach with high loads (≥80% 1RM) and low repetitions (4–8 reps). The reason is that this pattern maximizes neural adaptation and tendon stiffness while minimizing hypertrophy (and the associated weight gain). Research by Aagaard et al. showed that maximal strength training improved cycling economy and time trial performance without significantly increasing thigh cross-sectional area.

In terms of training volume, accumulating 6–10 sets per major movement per week, training 2–3 times per week, is considered by most meta-analyses to be the sweet spot balancing benefits and recovery. The table below presents a typical dose-response relationship:

Dose Range	Recommended Configuration	Applicable Period	Expected Benefit	Interference/Fatigue Risk
Minimum Effective Dose	1× per week, 2–3 sets per movement	Maintenance phase, in-season	Small	Low
Standard Effective Dose	2× per week, 3–4 sets per movement	Base phase, build phase	Medium–Large	Medium
High Dose	3× per week, 4–6 sets per movement	Off-season strength-specific phase	Large (but diminishing returns)	High (increased interference risk)

Individual differences play an important role here. Genetic polymorphisms (such as ACTN3, muscle fiber composition), training age, nutritional status, and recovery capacity all cause the same training plan to produce different results in different individuals. The “responder vs. low-responder” phenomenon commonly seen in research reminds us that dosage must be individualized and continuously monitored with objective indicators (such as 1RM progress, RFD, time trial performance). A practical principle is: establish a solid foundation at the minimum effective dose, then progressively increase through progressive overload, and decisively step back when poor recovery or stagnation in endurance performance appears.

Particularly 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 also why elite endurance athletes’ strength training doses are typically much more conservative than those of pure strength athletes—they pursue “sufficient” strength stimulus, not “maximal” strength stimulus.

Differences Across Populations

The benefits of Power Training for endurance sports are not “one-size-fits-all”; population characteristics significantly modulate the direction and magnitude of adaptation.

Beginners vs. Advanced Athletes. For strength training novices, the rapid early progress comes almost entirely from neural adaptation, with significant benefits that are easily obtained (the so-called “beginner gains”). However, for advanced athletes with years of training foundation, the neural system’s “ceiling” is lower, and continued progress often requires more sophisticated periodization, higher intensity, or new stimuli (such as 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 determine victory or defeat in competition.

Sex Differences. The research by Vikmoen et al. on female road cyclists is particularly important because early literature was predominantly male-focused. Results show that women equally benefit from strength training in terms of improved exercise economy and time trial performance, and because women start from a lower relative muscle mass baseline, some studies 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 muscle fibers and motor units (sarcopenia) transforms strength training from “icing on the cake” to “indispensable.” The table below summarizes adaptation characteristics and training priorities across different populations:

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

Understanding these differences allows athletes and coaches to avoid rigidly applying a single training plan to 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 plan requires answering four questions: which exercises to do, what intensity to use, 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 goals of Power Training for endurance sports, corresponding accessory exercises (such as eccentric components, plyometric jumps, or core stability training) can be added.

Intensity and Sets. When maximal strength is the primary goal, 4–6RM with 3–4 sets per movement and rest intervals of 3+ minutes between sets to ensure quality is recommended. If the goal leans toward power and RFD, switch to lighter loads (30–60% 1RM) combined with “maximal velocity intent” execution—movement speed itself is the stimulus. The table below shows an example off-season weekly schedule:

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

Scheduling. To reduce interference effects, 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 “capacity to be developed first” (early in the season, strength often comes first; mid-season, endurance often comes first).

Monitoring Indicators. 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 continuously declines or time trial performance stagnates, it 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 course, not to lift heavier in the gym. Keeping this hierarchy clear prevents strength training from taking over and eroding the recovery resources of endurance training.

Local Applications in Taiwan

Taiwan’s climate, terrain, and racing culture bring several unique considerations to the application of research on the transfer benefits of Power Training to slow-endurance sports.

Recovery management in hot and humid conditions. Taiwan’s summer heat and humidity can hinder recovery after strength training due to dehydration and reduced sleep quality. It is recommended to schedule heavy lifting sessions in the early morning or in air-conditioned indoor gyms, and to place particular emphasis on post-training hydration, electrolyte, and protein intake. Avoid stacking high-intensity endurance and strength stimuli simultaneously on hot afternoons, as this can exacerbate the interference effect.

Specific demands of climbing events. Classic Taiwanese events such as Wuling (West Approach), the North Route to Wuling, and the Yangmingshan series (Fengguizui, Balaka) are all renowned for their long distances and massive elevation gain. These events place extremely high demands on the muscular strength required to “sustain output at low cadence and high torque,” which is precisely the scenario where maximal strength and single-leg strength training can transfer directly. For challenges like Wuling, which involves elevation changes of up to three thousand meters, a reserve of lower-limb maximal strength allows riders to maintain pedaling capacity on the final steep slopes, avoiding the predicament of “legs giving out first.”

Local training resources and seasonal rhythm. Gyms are widespread in most Taiwanese counties and cities, allowing cyclists to make good use of free-weight areas for squats and deadlifts. Those training at home can also achieve similar stimuli using kettlebells, resistance bands, and bodyweight single-leg exercises. For riders whose primary training grounds are Yangmingshan, the Beiyi Highway, and the Central Cross-Island Highway, it is recommended to concentrate a dedicated strength block during the off-season (typically the hottest part of summer, when long outdoor sessions are less suitable), transforming the hot season into a golden window for building a strength foundation. Then, when autumn and winter bring cooler weather, return outdoors to convert that strength into actual riding performance. In this way, Taiwan’s unique seasonal rhythm can align perfectly with periodized strength training, becoming a strategic advantage for local athletes.

Debunking Common Myths

Regarding research on the transfer benefits of Power Training to slow-endurance sports, many claims circulating among enthusiasts do not align with academic evidence. The following clarifies each one.

Myth 1: “Lifting weights will make you bulky and heavier, dragging down your endurance.” Evidence shows that maximal-strength-oriented training (high intensity, low volume) primarily induces neural and tendon adaptations, with only limited increases in muscle cross-sectional area. In most studies, body weight does not change significantly; instead, performance improves due to enhanced efficiency.

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

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

Myth 4: “The interference effect of concurrent training will cancel out the benefits of strength training.” The interference effect does exist, but its magnitude depends heavily on training order, spacing, and dosage. With proper planning, strength and endurance can absolutely coexist and thrive together. By dispelling these myths, athletes can approach the training process with correct expectations and invest their limited time and energy where it truly pays off.

Conclusion

Looking at the evidence reviewed in this article, research on the transfer benefits of Power Training to slow-endurance sports is no longer a question of “whether to do it,” but rather “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 collectively support one conclusion: appropriate resistance training is an indispensable component of an endurance athlete’s toolkit.

Future research directions include using genetic and molecular markers to predict individual responses, clarifying the optimal molecular-level interval for concurrent training, and developing new resistance training equipment with greater sport specificity. For cyclists and runners in Taiwan, the most practical recommendation is: build a solid maximal strength foundation during the off-season, maintain it with the minimum effective dose during the season, and monitor progress with objective metrics throughout, so that strength truly translates into speed and endurance on race day. Science has already pointed the way; what remains is putting it into practice with every squat down and stand up.

Related Reading

• The Effect of Strength Training on Tendon Elastic Energy Return: An Ultrasound Elastography Study of the Achilles Tendon
• Site-Specific Benefits of Resistance Training on Bone Mineral Density: A Longitudinal Study of Regional Specificity
• The Effect of Maximal Strength on Endurance Performance: A Correlational Study of Peak Force and Cycling Efficiency
• The Effect of Strength Training on Ground Reaction Forces in Running: A Biomechanical Adaptation Study