Running Economy (RE) is the oxygen cost of running at a given speed. A 1% RE improvement can roughly translate into a 1% performance gain. This tool combines body-mass impact, body-fat reference ranges, and strength-training priorities.
Important: this tool does not encourage weight loss. Too-low body fat (men <5%, women <12%) can reduce performance and raise RED-S risk. Improve RE in this order: strength training, plyometrics, training volume, then body composition.
Personal Data
Sex
Age
Height (cm)
Weight (kg)
Body Fat (%)
Current 5K PR
Strength sessions per week
Evidence strength for improving RE:
- Strength training: strong (Beattie 2017 meta-analysis)
- Plyometrics: strong, 2-8% RE improvement in about 6 weeks
- Higher mileage: moderate, long-term adaptation
- Body composition: weaker, highly individual
- Strength training: strong (Beattie 2017 meta-analysis)
- Plyometrics: strong, 2-8% RE improvement in about 6 weeks
- Higher mileage: moderate, long-term adaptation
- Body composition: weaker, highly individual
BMI
22.5
VO2max Estimate
37.9
ml/kg/min
Body Fat Tier
-
Energy / km
65
kcal
Estimated Performance Impact of Body-Mass Change
Each 1 kg reduction might improve 5K by about 20 seconds (estimated from your current 5K time: 25:00)
Formula: time change is approximated by current time x (1 - (current_weight - new_weight) / current_weight x 0.85). Source: Bompa & Carrera (2005). The 0.85 factor approximates the gravity-related share of running energy cost.
Formula: time change is approximated by current time x (1 - (current_weight - new_weight) / current_weight x 0.85). Source: Bompa & Carrera (2005). The 0.85 factor approximates the gravity-related share of running energy cost.
Body composition looks reasonable. Focus RE improvements on strength work and training volume, not intentional weight loss.
Male Runner Body-Fat Reference
| Level | Body Fat | Notes |
|---|---|---|
| Elite | 5-10% | World-class marathoners; below 5% is medically risky |
| Competitive | 10-13% | Sub-elite and regional podium range |
| Serious Amateur | 13-17% | Advanced trained runners; many sub-3 marathoners |
| Healthy Amateur | 17-22% | Recommended range for recreational runners |
| High | >22% | May affect RE; pair fat loss with resistance training |
Men below 5% and women below 12% are near essential-fat limits and may risk hormonal disruption.
RE Improvement Checklist (Evidence-Weighted)
Add or increase strength training (2x/week)
Beattie 2017 shows strength training is one of the strongest RE interventions, even for elite runners. Endurance volume limits unwanted hypertrophy.
Add one plyometric session per week
Box jumps, bounding, and single-leg hops can improve RE by about 2-8% over short blocks. Add them after easy runs.
Build weekly volume gradually
Long-term mileage is associated with better RE. Keep weekly increases conservative to reduce injury risk.
Body composition is already reasonable
Intentional weight loss is not needed. Elite RE differences are driven more by neuromuscular efficiency than body-fat percentage.
Use running drills 1-2x/week
A-skips, B-skips, high knees, bounds, and strides can improve neuromuscular coordination and indirectly improve RE.
Runner Strength Template (2x/week)
Main lifting session:
Plyometrics (1x/week after an easy run):
- Squat / reverse lunge: 4x4-6 reps @ 80-85% 1RM
- Single-leg deadlift: 3x6 reps each side
- Loaded calf raise: 3x8 reps
- Core: plank 60s x 3 + dead bug 10x3
Plyometrics (1x/week after an easy run):
- Box jump: 3x5
- Single-leg hops: 3x10 each side
- Bounding: 4x30m
- If you have knee history, use smaller pogo hops instead
Beattie et al. (2014) found in a systematic review that strength training can improve RE by about 2-8%. Elite runners use it too; endurance volume naturally limits large muscle gain.
Research Basis
- Beattie et al. (2014):Sports Medicine systematic review: strength training, including plyometrics, improves RE even in elite athletes.
- Saunders et al. (2004):Sports Med review: body composition is a secondary RE factor; neuromuscular efficiency and tendon stiffness matter more.
- Foster & Lucia (2007):Sports Med: world-class marathoners often sit around BMI 19-21, with low but not medically unsafe body-fat ranges.
- Bompa & Carrera (2005):Periodization Training for Sports: a 1% body-mass change is not a 1:1 performance change; running energy cost responds more modestly.