The recently published article in Diabetes by Pataky et al. (1) delves into the underlying mechanisms of three exercise modalities and their impact on insulin resistance, offering valuable insights into the potential identification of optimal exercises to combat this prevalent health issue. However, while the study presents intriguing findings, I would like to raise some concerns regarding participant characteristics and the study protocol, which I believe warrant further consideration.

First, the recruitment of lean subjects with a BMI <32 kg/m2 as the defining parameter raises concerns, as BMI may not accurately reflect body composition, leading to variations in metabolic characteristics and cellular muscle profile. Research has shown significant differences in BMI between racial groups, such as African Americans and European Americans, which may play a crucial role in the risk of developing insulin resistance related to adiposity (2,3). Additionally, it is essential to include information about the subjects’ occupations or daily activities that may influence the involvement of the vastus lateralis muscle throughout the day.

Second, the article discusses an increase in branched-chain amino acids in muscle tissue, but not in the plasma, after high-intensity interval training. Given the significance of amino acids and lipids in the metabolomic profile parameters, this raises questions about whether standard liver tests were conducted at baseline to ensure subjects exhibited nonpathological conditions. Unhealthy drinking habits or underlying diseases affecting branched-chain amino acid levels should be ruled out to provide a more accurate representation of the study population.

Lastly, the article lacks information on the subjects’ adherence to the protocol during the 12-week study period. Details regarding attendance at exercise sessions, dietary control (if implemented), and sleep/rest profiles are crucial for a comprehensive understanding of the study outcomes. Clarifying these aspects would enhance the validity and applicability of the findings, especially from the biopsy samples (4).

I appreciate the effort put forth by Pataky et al. in conducting this valuable research, and I believe addressing these concerns and inquiries would contribute to the overall robustness of the study.

Duality of Interest. No potential conflicts of interest relevant to this article were reported.

1.
Pataky
MW
,
Kumar
AP
,
Gaul
DA
, et al
.
Divergent skeletal muscle metabolomic signatures of different exercise training modes independently predict cardiometabolic risk factors
.
Diabetes
2024
;
73
:
23
37
2.
Newton
RL
Jr
,
Zhang
D
,
Johnson
WD
, et al
.
Predictors of racial differences in weight loss: the PROPEL trial
.
Obesity
2024
;
32
:
476
485
3.
Yurchishin
ML
,
Fowler
LA
,
Parcha
V
,
Arora
P
,
Garvey
WT
,
Gower
B.
223-LB: Associations between genetic risk for insulin resistance and measured insulin sensitivity are impacted by race and BMI status
.
Diabetes
2023
;
72
(
Suppl_1
):
223
LB
4.
Hulston
CJ
,
Wolsk
E
,
Grøndahl
TS
,
Yfanti
C
,
Van Hall
G.
Protein intake does not increase vastus lateralis muscle protein synthesis during cycling
.
Med Sci Sport Exerc
2011
;
43
:
1635
1642
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