Effect of Citrulline Malate Supplementation on Physical Function and Biochemical Parameters in Physically Active Older Women

Handgrip strength (kg) was assessed with a digital handheld dynamometer (JAMAR®, 0-90 kg; Performance Health, Warrenville, IL, USA), by standardised procedures.

Cardiorespiratory fitness was evaluated using the six-minute walk test (6MWT) on a standardised indoor 400-metre track.

Gait speed was measured over four metres using photoelectric timing gates. Participants began walking five metres before the start line to ensure a consistent pace throughout the timed section.

Lower limb strength was assessed using the Five Times Sit-to-Stand Test (5xSTS), which involved recording the time taken to rise from a 45 cm highchair five times as quickly as possible without using the arms for support.

Balance was assessed via static balance testing in three different stances, held for 10 seconds each: side-by-side, semi-tandem and tandem

Frailty and global physical function were evaluated using the Short Physical Performance Battery (SPPB), which incorporates tests of gait speed, balance, and the ability to rise from a chair. Based on the total score obtained in all tests (range from 0 to 10), participants are identified as having severe limitations (0-4), moderate limitations (4-6), mild limitations (7-9) and minimal limitations (10-12).

High-density lipoprotein (HDL) was evaluated to explore potential cardiovascular implications.

Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain). A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing. All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Creatine kinase was measured as an indicator of muscle damage.

Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain).

A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing.

All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Liver enzyme activity was assessed via serum levels of aspartate aminotransferase (AST/GOT) and alanine aminotransferase (ALT/GPT).

Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain).

A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing.

All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Low-density lipoprotein (HDL) was evaluated to explore potential cardiovascular implications.

Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain). A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing. All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Glucose provided insight into metabolic regulation. Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain). A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing. All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Testosterone was used to evaluate the hormonal status and potential anabolic-catabolic shifts.

Venous blood samples were collected under standardised conditions between 08:00 and 08:30 a.m., following a minimum of 12 hours' fasting and at least eight hours' rest overnight. All extractions were performed by a certified nurse at an accredited clinical laboratory (Det Norske Veritas, certification no. 18031, Spain). A total of 10 ml of serum was drawn into clot-activator tubes, centrifuged and stored at -20 °C until analysis. Meanwhile, 3-5 mL of plasma was collected in EDTA® tubes and refrigerated at 4 °C for subsequent processing. All analytical procedures were conducted using standardised and validated platforms. Haematological assessments were performed using the Coulter Counter MAX-M® system, while biochemical and hormonal analyses were conducted using the Architect 2000® analyser (Abbott Diagnostics).

Quality of life was measured using the World Health Organization Quality of Life Questionnaire - Brief Version (WHOQOL-BREF). The scale ranges from 0 to 100. Higher scores indicate a higher quality of life.