Question explored with the scientific record
growing the knee
You cannot grow the knee bone itself once your growth plates have closed. What you can grow is the quadriceps muscle that sits over and around it, and resistance training does that reliably.
The knee's visible size is mostly muscle and some joint structure. After puberty, bone length is fixed; growth hormone therapy only helps children with true deficiency, and it carries real risks like insulin resistance [8] and, in rare case reports, tumors during treatment [7]. So for an adult, the honest target is the quadriceps.
The training evidence is consistent. Six months of leg training grew the quadriceps about 9% in cross-section, almost entirely from the fast type II fibers swelling [1]. Heavier training beat light training with blood-flow restriction for strength, though both grew muscle similarly [2]. Training through the stretched part of the range (deep knee bends) produced more growth than partial top-range reps [3]. Slow, grinding sets that lose velocity grew more muscle than snappy sets, at a cost to jump performance [6]. Eccentric overload work grew muscle volume about 6% in weeks [5]. Protein alongside rehab training helped ACL patients gain more muscle than carbs or placebo [4].
| Method | Muscle gain | Note |
|---|---|---|
| Standard heavy training | ~9% CSA in 6 months [1] | Best strength gains [2] |
| Deep-range knee extensions | greater than partial range [3] | Region-specific growth [3] |
| Eccentric overload | ~6% volume quickly [5] | Fast early gains |
| High-velocity-loss squats | ~10.5% fiber CSA [6] | Less explosive power |
One caveat: this retrieval surfaced no studies on growing the knee joint or bone size specifically in adults, so I cannot cite anything there. If the goal is appearance, train the quads deep and heavy and eat enough protein. If the goal is actual bone or joint enlargement, no evidence supports any method.
My call: grow the muscle, not the knee; that is the only part that responds. Confidence: high for muscle growth, and the bone-growth question has no supporting evidence at all.
Sources used 8
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The decline in skeletal muscle mass with aging is mainly attributed to a reduction in type II muscle fiber size
This study demonstrates that age-related skeletal muscle mass loss in healthy men is primarily due to smaller type II muscle fibers rather than a loss of muscle fibers, and that six months of resistance training increases quadriceps cross-sectional area entirely through hypertro…
DOI: 10.1016/j.exger.2013.02.012 -
Comparisons Between Low-Intensity Resistance Training With Blood Flow Restriction and High-Intensity Resistance Training on Quadriceps Muscle Mass and Strength in Elderly
This study compares the effects of low-intensity resistance training with blood flow restriction (LRT-BFR) and high-intensity resistance training (HRT) on quadriceps muscle mass and strength in elderly individuals, finding that both methods are effective but HRT leads to greater…
DOI: 10.1519/JSC.0000000000000703 -
Partial range of motion training elicits favorable improvements in muscular adaptations when carried out at long muscle lengths
A 12-week randomized trial in 45 untrained young women compared knee-extension training across four ranges of motion (INITIAL ROM, FINAL ROM, FULL ROM, VAR ROM) plus a control, assessing regional quadriceps hypertrophy via ultrasound and angle-specific strength (1RM) across mult…
DOI: 10.1080/17461391.2021.1927199 -
The effect of protein and carbohydrate supplementation on strength training outcome of rehabilitation in ACL patients
This study investigates the effects of protein and carbohydrate supplementation on muscle hypertrophy and strength outcomes in ACL-injured patients undergoing rehabilitation through resistance training, finding that protein supplementation significantly enhances these outcomes c…
DOI: 10.1002/jor.20147 -
Resistance training using eccentric overload induces early adaptations in skeletal muscle size
This study investigates the effects of resistance training using eccentric overload compared to traditional weight stack training on muscle size and strength adaptations in healthy men.
DOI: 10.1007/s00421-007-0583-8 -
Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations
The study compared two velocity-loss based resistance-training programs (20% vs 40% velocity loss per set) over 8 weeks in young men performing squats, finding that the 20% loss yielded similar strength gains with greater jump performance and less hypertrophy, while the 40% loss…
DOI: 10.1111/sms.12678 -
Malignant thymoma in a patient with growth hormone deficiency during growth hormone therapy
This case study reports the occurrence of malignant thymoma in an 8-year-old boy with growth hormone deficiency who had been undergoing growth hormone therapy for over three years, suggesting a potential link between the therapy and the development of malignancies.
DOI: 10.1007/BF02073374 -
Insulin Sensitivity in Adults with Growth Hormone Deficiency and Effect of Growth Hormone Treatment
This study investigates the metabolic effects of growth hormone (GH) deficiency in adults and the impact of GH treatment on insulin sensitivity, revealing that GH induces insulin resistance while also promoting beneficial changes in body composition.
DOI: 10.1159/000089317