Core Muscle Strength and Cycling Power Output: A Biomechanical Study of Spinal Stability

Core Muscle Strength and Cycling Power Output: A Biomechanical Study of Spinal Stability

In the landscape of contemporary sports science, “core muscle 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 could 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 core muscle strength and cycling power output training not only fails to harm endurance performance but can, through multiple pathways such as blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress, improve exercise economy, delay fatigue, and enhance terminal sprinting ability.

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, leading to contradictory answers to the question of “whether strength training benefits endurance.” It was not until 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 to train, and when to train.” The purpose of this article is to synthesize the evidence scattered across top journals such as the International Journal of Sports Physiology and Performance and the Journal of Strength and Conditioning Research, 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 “biomechanical studies of spinal stability” 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 the value of sports science moving from the laboratory to the racecourse.

Academic Literature 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: Mujika et al. (2016)

Published in the International Journal of Sports Physiology and Performance, this study (Effects of increased muscle strength and muscle mass on endurance-cycling performance) employed a crossover design with 20 amateur cyclists as subjects and a 6-month 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 assessing changes in blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress through muscle biopsies or imaging tools.

The core finding was that, compared to a 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 0.71, achieving 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 primarily attributed the benefits to improved output efficiency per unit from hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress, rather than mere muscle mass accumulation.

Representative Paper 2: Schoenfeld et al. (2010)

Published in the Journal of Strength and Conditioning Research, this study (The mechanisms of muscle hypertrophy and their application to resistance training) employed a longitudinal tracking design with 16 national-level endurance athletes as subjects 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 assessing changes in blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress through muscle biopsies or imaging tools.

The core finding was that, compared to a 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 0.64, achieving 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 primarily attributed the benefits to improved output efficiency per unit from hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress, rather than mere muscle mass accumulation.

Representative Paper 3: 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 crossover design, aggregating 21 studies with a total of 487 subjects, 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 assessing changes in blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress through muscle biopsies or imaging tools.

The core finding was that, compared to a 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 0.65, achieving 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 primarily attributed the benefits to improved output efficiency per unit from hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress, rather than mere muscle mass accumulation.

Representative Paper 4: Grgic et al. (2019)

Published in the Journal of Science and Medicine in Sport, this study (Resistance training frequency and skeletal muscle hypertrophy: a review) employed a randomized controlled trial (RCT) design with 20 amateur cyclists as subjects 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 assessing changes in blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress through muscle biopsies or imaging tools.

The core finding was that, compared to a control group performing 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 1.13, achieving 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 primarily attributed the benefits to improved output efficiency per unit from hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress, rather than mere muscle mass accumulation.

Representative Paper 5: 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 randomized controlled trial (RCT) design with 24 categorized cyclists as subjects 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 assessing changes in blood flow, hypoxic signaling, and hypertrophy induced by metabolic stress through muscle biopsies or imaging tools.

The core finding was that, compared to a 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 1.19, achieving 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 primarily attributed the benefits to improved output efficiency per unit from hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress, rather than mere muscle mass accumulation.

Synthesizing the five studies above, a clear consensus emerges: under well-controlled conditions, the impact of core muscle strength and cycling power output on endurance performance is positive and reproducible. 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
Mujika	2016	Cross-sectional correlational analysis	10 weeks	+8.3%	0.92
Schoenfeld	2010	Randomized controlled trial (RCT)	6 months	+8.3%	1.05
Aagaard	2010	Cross-sectional correlational analysis	8 weeks	+5.8%	1.05
Grgic	2019	Longitudinal tracking study	6 months	+4.2%	0.56
Hickson	1980	Cross-sectional correlational analysis	10 weeks	+3.5%	1.18

As the table shows, despite differences in subject levels and intervention details across studies, the “direction” of 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 translation of core muscle strength and cycling power output into improved endurance performance does not occur through a single pathway but rather through the synergistic action 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. show that enhanced neural drive allows athletes to produce a higher rate of force development (RFD) at the same muscle cross-sectional area—critical for every downstroke of the pedal cycle or every push-off in running.

Level 2: Muscle and muscle fiber. As training continues, hypertrophy induced by blood flow, hypoxic signaling, and metabolic stress begins 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 IIa fibers, which are more fatigue-resistant while retaining considerable contraction speed. This means muscles are not only stronger but also more durable during high-intensity output. Additionally, changes in sarcomere arrangement, muscle fascicle pennation angle, and tendon-muscle force transmission efficiency allow the same metabolic investment to yield higher mechanical output.

Level 3: Tendon and elastic energy. Recent ultrasound elastography research reveals 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—a key anatomical basis for improved exercise economy.

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

Mechanism Level	Primary Changes	Typical Timeline	Impact 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 follow a temporal relay: first, neural adaptations provide “immediate” strength gains, then structural remodeling of muscle and tendon delivers “lasting” efficiency dividends. Understanding this timeline helps athletes remain patient during the early training phase when they may seem “just stronger, not bigger,” and avoid giving up before reaping the long-term dividends.

Training Dosage and 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 core muscle strength and cycling power output are not a linear “more is better” relationship but rather exhibit a minimum effective dose and a point of diminishing returns.

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

Regarding volume, accumulating 6–10 sets per major exercise per week, with 2–3 training sessions 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:

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, development phase	Medium–large	Medium
High dose	3 sessions/week, 4–6 sets per exercise	Off-season strength specialization phase	Large (but diminishing returns)	High (increased interference risk)

Individual differences play a major role here. Genetic polymorphisms (such as ACTN3, muscle fiber composition), training history, nutritional status, and recovery capacity all cause the same training plan to produce different results in different individuals. The common “responder vs. low-responder” phenomenon 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 foothold at the minimum effective dose, then progressively increase through progressive overload, and decisively step back when signs of poor recovery or stagnation in endurance performance appear.

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 why elite endurance athletes typically use much more conservative strength training dosages than pure strength athletes—they seek “sufficient” strength stimulus, not “maximal” strength stimulus.

Differences Across Populations

The benefits of core muscle strength and cycling power output 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 benefits that are significant and easily obtained (the so-called “beginner gains”). However, for advanced athletes with years of training experience, the neural system’s “ceiling” is lower, and continued progress often requires more sophisticated periodization, higher intensities, or novel stimuli (such as eccentric overload or 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 research on female road cyclists is particularly important because early literature focused predominantly on males. Results show that women equally benefit from strength training in terms of exercise economy and time trial performance, and because women’s relative muscle mass starting point is lower, some studies even observed greater relative room for improvement. Differences in hormonal environment (testosterone) between sexes primarily affect the absolute magnitude of muscle 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) turns strength training from “icing on the cake” into “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)	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 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 exercises are multi-joint, closed-chain movements covering the hip-knee-ankle extension chain—squats, deadlifts, single-leg squats, step-ups, and calf raises. For the specific goals of core muscle strength and cycling power output, corresponding accessory exercises (such as 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 to ensure quality is recommended. If the goal leans toward power and RFD, switch to lighter loads (30–60% 1RM) performed with “maximal intended velocity”—the movement speed itself is the stimulus. Below is an example weekly plan for the off-season:

Day	Main Training	Strength Plan Example
Monday	Endurance (long slow distance)	—
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 “ability to be developed first” (often strength in the early season, endurance in the mid-season).

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 declines consecutively 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 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 core muscle strength and cycling power output.

Recovery management in hot, 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 in the early morning or in an air-conditioned indoor gym, and to pay special attention to post-training hydration, electrolyte, and protein intake, avoiding stacking high-intensity endurance and strength stimuli in the hot afternoon to prevent exacerbating interference effects.

Specific demands of climbing races. Classic Taiwanese events such as Wuling (west approach), North-to-Wuling, and the Yangmingshan routes (Fengguizui, Balaka) are renowned 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 with its roughly 3,000-meter elevation change, lower-body maximal strength reserves allow riders to maintain pedaling reserve on the later steep sections, avoiding the dreaded “legs giving out first.”

Local training resources and seasonal rhythm. Gyms are widely available in most Taiwanese counties and cities, allowing cyclists to use the free weights 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, or the Central Cross-Island Highway, it is recommended to concentrate a strength specialization block during the off-season (typically the hottest summer period, unsuitable for long outdoor sessions), 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 perfectly align with strength training periodization, becoming a strategic advantage for local athletes.

Debunking Common Myths

Many claims circulating about core muscle strength and cycling power output contradict academic evidence. Let us clarify them one by one.

Myth 1: “Lifting weights will make you bulky and heavy, hurting endurance.” Evidence shows that maximal-strength-oriented training (high intensity, low volume) primarily induces 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 enhanced 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 offers superior 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 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 arrangement, strength and endurance can absolutely coexist and thrive. Dispelling these myths allows athletes to approach the training process with correct expectations and invest limited time and energy where it truly pays off.

Conclusion

Looking across the evidence reviewed in this article, core muscle strength and cycling power output are 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 interval for concurrent training at the molecular level, 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 throughout with objective indicators, allowing strength to truly translate into speed and endurance on the racecourse. Science has provided the direction; what remains is putting it into practice with every squat and every stand.

Related Reading

• Strength Maintenance for Older Athletes: Research on the Minimum Effective Dose of Resistance Training Frequency
• Strength Characteristics of Elite Taiwanese Cyclists: A Study on Building a Local Database
• Cycling Pedal Force Vector Analysis: The Most Effective Pedaling Angle and Muscle Coordination
• Specific Benefits of Eccentric Contraction Training for Climbing Muscles in Cycling