REF-1155 · Albracht & Arampatzis, 2013 · European Journal of Applied Physiology · Paper · PubMed

Heavy isometric calf training made running about 4% cheaper

14 weeks of 90% MVC isometric plantarflexion (5 × 4 × 3 s, 4×/week) raised plantarflexor strength ~7% and triceps surae tendon stiffness ~16% and cut the oxygen cost of running at 3.0 and 3.5 m/s ~4% in male runners, with running kinematics unchanged

Blimited evidenceMeasured on recreational to trained athletes

Albracht and Arampatzis asked whether making the triceps surae stronger and its tendon stiffer would change running economy. Thirteen runners added a 14-week plantarflexor programme to their running while 13 controls kept their usual training. Maximal isometric plantarflexion strength rose about 7% and triceps surae tendon-aponeurosis stiffness about 16%.

The rate of oxygen consumption and the energy cost of running fell about 4% at 3.0 and 3.5 m/s in the exercise group and did not change in the controls. Running kinematics, gastrocnemius medialis fascicle length and the elongation of the series-elastic element during stance did not change.

The authors suggest that a stiffer tendon that stretches as much as before stores and returns more energy, and that muscular output is redistributed in the leg. The abstract calls the programme "resistance training"; the citing papers, including the authors' own group, describe it as isometric.

Protocol

Is it isometric? Yes, by four citing sources; the abstract does not say so.
REF-1156 Bohm 2021, full text, same research group: "the same 14-week muscle–tendon training" as this study, i.e. isometric ankle plantarflexion at 90% of MVC, five sets of four 3-s contractions with 3 s of relaxation.
REF-517 Bohm 2015, full-text Table 2: isometric (repetitive), 90% MVC, 3 s, 4 repetitions, 5 sets, 14 weeks, 4 times a week; 13 men, runners; stiffness +15.8% (p < 0.05).
REF-801 Llanos-Lagos 2024, full-text Table: isometric ankle plantarflexion, 90% MVC, 5 × 4 × 3 s, 3 s rest, 14 weeks, 4 sessions a week, 56 sessions; 13 men, moderately trained.
REF-1152 Lazarczuk 2022, full-text table: "high intensity, low volume" isometric, 14 weeks, 4 times a week; 27 ± 5 y, 180 cm, 76 kg.
Exercise: overcoming isometric ankle plantarflexion (pushing against a fixed resistance), 90% of MVC, 3-s contractions with 3 s rest, 4 per set, 5 sets; 4 sessions a week for 14 weeks, added to running. Joint angle not available.
Control: 13 runners who did not change their training.
Running test: rate of oxygen consumption and energy cost at 3.0 and 3.5 m/s (10.8 and 12.6 km/h).
Other measures: maximal isometric plantarflexion strength; tendon-aponeurosis stiffness by ultrasound; running kinematics; gastrocnemius medialis fascicle length and series-elastic element elongation during running.

Key Results

Outcome (14 weeks)Exercise group (n = 13)Control group (n = 13)Source
Maximal plantarflexion strength~+7%—abstract
Tendon-aponeurosis stiffness~+16% (+15.8%, p < 0.05)—abstract; REF-517 Table 2
O2 consumption and energy cost~-4%, significantno changeabstract
Energy cost at 10.8 km/h, J/m/kg4.25 ± 0.34 → 4.05 ± 0.32 (-4.7%)4.11 ± 0.32 → 4.11 ± 0.28REF-801 full-text table
Energy cost at 12.6 km/h, J/m/kg4.27 ± 0.32 → 4.12 ± 0.31 (-3.5%)4.18 ± 0.34 → 4.19 ± 0.30REF-801 full-text table
Kinematics, GM fascicle length, SEE elongationunchanged—abstract
The percentage changes in the energy-cost rows are our arithmetic from REF-801's extracted means. The abstract gives no p-values and does not say whether the group × time interaction was tested.

Mechanisms

Measured: strength and tendon stiffness rose; economy improved; stride kinematics and the stretch of the series-elastic element during stance did not change.
Authors' interpretation: the same stretch of a stiffer tendon means more elastic energy stored and returned per step, together with a redistribution of muscular output within the leg, which may explain the lower cost.
Replication's interpretation ([REF-1156]): with the same programme, the soleus fascicles shortened at velocities closer to their peak efficiency (enthalpy efficiency +7% over stance).
Inference: the exercise group started less economical than the controls (4.25 vs 4.11 J/m/kg at 10.8 km/h), so part of the fall could be regression toward the mean.

Practical Application

Can heavy isometric calf work make running cheaper? In 26 male runners (not stated as randomised), 14 weeks of 90% MVC 3-s calf holds 4×/week cut running cost ~4%; pooled with two other isometric studies, the effect was not significant. The pooled estimate is in REF-801; a replication is REF-1156.
The programme: isometric calf push at 90% of maximal voluntary force, 3 s on and 3 s off, 4 per set, 5 sets, 4 sessions a week for 14 weeks, on top of normal running. That is 20 loaded contractions, 60 s under load, per session (our arithmetic; rest between sets is not reported).
A later trial by the same group with the same programme found the same ~4% fall in running cost, though the comparison with controls was not significant (REF-1156).
Not from this paper; the base's practice: treat heavy isometric calf work as an add-on to the heavy multi-joint lifting that has the stronger economy evidence (REF-801, SYNTH-44), not as a replacement, and expect any economy change at easy speeds, the only speeds tested here.

Limitations

Small (13 vs 13); randomisation not stated in the abstract; no blinding reported.
Read from the abstract; the protocol comes from four citing papers and the energy-cost means from REF-801's extraction, not from this paper's text.
No p-value or interaction test in the abstract; the exercise group's baseline cost was higher than the controls'.
Men only; training status loosely described (VO2max not reported in REF-801's table); economy at two easy speeds only, no time trial.
No group did a time-matched alternative, so the effect of extra supervised sessions is not separated from the specific training.
Funding and conflicts of interest are not stated in the abstract.
How this entry was checked and changed
Why this level

parallel controlled trial, n=26 (13 + 13), allocation method not stated; from the abstract (no open full text); the programme is described from four citing papers, labelled below