Ashwagandha & HIIT: Does It Boost Your Workout?

Key Findings

This study found no significant additional benefits from ashwagandha supplementation beyond those achieved through HIIT alone. While both the ashwagandha and placebo groups demonstrated large, statistically significant improvements in aerobic capacity parameters (test time, maximal aerobic power, anaerobic threshold) after 8 weeks of training (main effect of time: P = 0.00001; within-group pre-post P < 0.001), there was no main effect of group (P > 0.05) and no significant interaction between time and group (P > 0.05) for aerobic capacity, muscle oxygenation, or haematological parameters. Ashwagandha (600 mg/day) did not enhance HIIT-induced adaptations compared to placebo.

Study Design

This was a randomized, double-blind, placebo-controlled trial with a 2 × 2 factorial design (time × group). It included 33 healthy male non-athletes (ashwagandha: n = 17; placebo: n = 16) who underwent 8 weeks of supervised HIIT. Training consisted of 3 rowing ergometer sessions/week, each involving 5–7 sets of 1.5-minute intervals at 85–95% of maximum aerobic power, with 1.5-minute rest intervals at 70 W. Outcomes were assessed via maximal graded exercise tests (pre- and post-intervention) with muscle oxygenation measured via near-infrared spectroscopy (NIRS) and haematological parameters analyzed from resting blood samples.

Dosage & Administration

Participants in the intervention group received 600 mg/day of ashwagandha extract, administered orally in divided doses (timing unspecified). The placebo group received an identical-looking inert substance. Supplementation duration matched the 8-week HIIT program. The extract type (e.g., root vs. leaf, standardization) was not detailed in the provided summary.

Results & Efficacy

HIIT significantly improved aerobic capacity in both groups:
- Test time: Large increases (P < 0.001 within groups).
- Maximal aerobic power: Significant gains (P < 0.001 within groups).
- Anaerobic threshold: Significant improvements (P < 0.001 within groups).
However, no between-group differences were observed for these outcomes (P > 0.05). Haematological parameters (e.g., hemoglobin, hematocrit) and muscle oxygenation metrics also showed no significant group effects or interactions (P > 0.05). Effect sizes for time effects were large (partial eta-squared [η²] reported but value incomplete in source summary), but ashwagandha conferred no additional efficacy.

Limitations

Key limitations include:
1. Homogeneous sample: Only healthy, young male non-athletes were studied, limiting generalizability to women, older adults, or athletes.
2. Short duration: An 8-week intervention may be insufficient to detect subtle physiological adaptations.
3. Unspecified extract details: Lack of information on ashwagandha extract composition (e.g., withanolide concentration) hinders reproducibility.
4. Incomplete outcome reporting: Muscle oxygenation results were mentioned but not quantified in the summary. Future research should explore longer durations, diverse populations, and mechanistic pathways (e.g., inflammation, oxidative stress).

Clinical Relevance

For supplement users, this study indicates that 600 mg/day of ashwagandha does not augment HIIT-induced improvements in aerobic capacity, muscle oxygenation, or blood parameters in healthy men. While HIIT alone robustly enhanced fitness, adding ashwagandha provided no measurable ergogenic benefit for these outcomes. Users seeking performance enhancement through HIIT should prioritize consistent training over ashwagandha supplementation for aerobic adaptations. However, this does not preclude potential benefits for other outcomes (e.g., stress reduction, strength) or different populations. Consultation with a healthcare provider before starting supplementation is advised.