Authors’ Response: Additional Analyses of Nutritional Intake and Muscle Strength in Individuals with Airflow Limitation

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Tuberc Respir Dis. 2025;88(2):411-412

Publication date (electronic) : 2025 February 6

doi : https://doi.org/10.4046/trd.2024.0184

I Re Heo, M.D., Ho Cheol Kim, M.D., Ph.D.

Department of Internal Medicine, Gyeongsang National University Changwon Hospital, Gyeongsang National University College of Medicine, Changwon, Republic of Korea

Address for correspondence Ho Cheol Kim, M.D., Ph.D. Department of Internal Medicine, Gyeongsang National University Changwon Hospital, Gyeongsang National University College of Medicine, 11 Samjeongja-ro, Seongsan-gu, Changwon 51472, Republic of Korea Phone 82-55-214-3730 Fax 82-55-214-8618 E-mail hochkim@gnu.ac.kr

Received 2024 December 3; Accepted 2025 January 11.

First, adjusting nutritional intake for body weight

In response to the suggestion to adjust nutritional intake according to body weight, we reanalyzed our data using weight-adjusted values (e.g., g/kg or kcal/kg). This reanalysis yielded results consistent with those reported in the original manuscript. Participants engaging in active aerobic physical activity (PA) consistently showed higher intakes of total food, water, protein, and lipids compared to those not engaged in active PA. Similarly, individuals with low handgrip strength (HGS) exhibited lower nutritional intakes than those with normal HGS. However, although the trends remained consistent, the strength of the associations between weight-adjusted nutritional intake and HGS did not significantly improve. In some instances, the correlation coefficients were slightly weaker than those observed in the original analysis using absolute values (Tables 1, 2). These findings indicate that while weight adjustment provides a more personalized measure of dietary intake, it may not significantly alter the overall interpretation of the relationship between nutritional intake and muscle strength.

Table 1.

Comparison of nutritional intake adjusted body weight according to aerobic physical activity and HGS

Table 2.

The correlation coefficient between HGS and nutritional component intake adjusted body weight

Second, subgroup analysis: no-active PA participants

The analysis of the subgroup of participants without active PA provided further insights. Notably, the correlation coefficients for water and protein intake with HGS were stronger in this subgroup compared to the overall analysis. Specifically, the correlation between water intake and HGS was more pronounced in the non-active PA group, suggesting that hydration plays a critical role in muscle function for individuals with limited PA. Similarly, protein intake demonstrated a stronger association with HGS in this subgroup, highlighting the importance of adequate protein consumption in maintaining muscle strength among less active individuals (Table 3).

Table 3.

The correlation coefficient between HGS and nutritional component intake among no-aerobic physical activity individuals

Third, HGS cut-off values

Regarding the HGS cut-off values utilized in our study, it is pertinent to note that these values were derived from the Korean National Health and Nutrition Examination Survey (KNHANES VI). We referenced the study by Yoo et al. [2], which analyzed HGS in a representative cohort of the Korean population and established sarcopenia cut-off values for healthy adults. Utilizing these cut-off values aimed to maintain consistency with prior research and to apply criteria that are most applicable to the Korean population. However, we recognize that these thresholds may not adequately reflect the unique characteristics of individuals with airflow limitation, who frequently exhibit diminished muscle strength due to their underlying condition.

In conclusion, the reanalyzed data indicate that the associations between water and protein intake with HGS are more pronounced in the non-active PA subgroup compared to the overall cohort. Although the broader trends are consistent, these findings specific to the subgroup enhance our comprehension of the interplay between nutrition and muscle strength in individuals with airflow limitation. We are grateful to Dr. Ming-Che Chang and colleagues for their invaluable feedback, which facilitated the refinement of our analyses and the revelation of further insights.

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