L-serine and Strength Training in the Elderly

Global cognitive performance will be assessed using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), a standardized neuropsychological test battery that evaluates multiple cognitive domains including memory, attention, language, and visuospatial abilities.

The primary outcome is the RBANS Total Scale Index score, which summarizes performance across the RBANS cognitive domains. RBANS index scores are standardized scores with a mean of 100 and a standard deviation of 15, typically ranging from approximately 40 to 160. Higher scores indicate better cognitive performance.

The RBANS provides standardized index scores (mean = 100, standard deviation = 15) that typically range from approximately 40 to 160, with higher scores indicating better cognitive performance. The following RBANS domain indices will be evaluated: Immediate Memory Index, Visuospatial/Constructional Index, Language Index, Attention Index, and Delayed Memory Index.

Concentric isokinetic peak torque (in newton meters, Nm) will be assessed for knee extension, knee flexion, and hip extension and flexion using an Isoforce dynamometer (TUR GmbH, Hohen Neuendorf, Berlin).

All isokinetic measurements will be performed on the dominant leg and with 4 consecutive repetitions at maximal effort of extension and flexion.

Testing the knee will be performed over a range of motion (ROM) of 20 degrees-100 degrees at angular velocities of 60 degrees/s , and 180 degrees/s.

Testing the hip will be performed over a range of motion (ROM) of 20 degrees- 90 degrees at angular velocities of 60 degrees/s , and 180 degrees/s.

The minimum possible torque is 00 Nm; higher values indicate better muscle strength.

Isometric handgrip strength will be measured in kilograms (kg) using a JAMAR-compatible handgrip dynamometer adjustable to different grip widths. Testing will be performed seated. Each trial consists of a maximal isometric contraction held for 4-5 seconds; two trials will be conducted with the dominant and subsequently with the non-dominant hand, with 1-2 minutes rest between trials. The minimum possible value is 00 kg; higher values indicate better grip strength. Results will be recorded per trial; the analysis will use the highest value from the two trials (peak grip strength, kg).

The 30-Second Arm Curl Test assesses the number of full elbow-flexion repetitions completed in 30 seconds with a standardized dumbbell while seated.

Women use a 5 lb (2.3 kg) dumbbell; men use an 8 lb (3.6 kg) dumbbell. Participant sits upright near the front edge of a chair without armrests, back straight, feet flat on the floor, holding the dumbbell in the dominant hand with a supinated grip. After instruction and demonstration, the participant performs 2-3 practice repetitions. Following a 60-second rest, the timed test begins on the assessor's signal. The starting position is full elbow extension (down); the end position is full elbow flexion (up). Count only repetitions that complete the full range of motion (ROM). A repetition initiated in the final second (second 30) is counted as valid if more than 50% of the ROM is completed.

Minimum possible value is 0 repetitions; there is no predefined maximum.

The Back Scratch Test assesses shoulder, shoulder-girdle, and thoracic spine flexibility. While standing, one hand is placed over the shoulder and down between the shoulder blades; the other hand reaches up the back. The linear distance between the tips of the middle fingers is measured along the spine using a tape measure.

Record the distance in centimeters (cm) with sign convention: positive values indicate fingertip overlap; zero indicates fingertips just touch; negative values indicate a gap between fingertips. There is no predefined minimum or maximum (values can range from negative to positive depending on flexibility and anthropometrics). Higher (more positive) values indicate better flexibility.

Back Scratch distance (cm), dominant side (specify side assessed in the protocol). Use the same side and method at all time points.

The participant sits at the front edge of a stable chair placed against a wall (seat height approximately 45-46 cm). One leg is flexed at the knee with the foot flat on the floor; the other leg is extended at the knee with the ankle dorsiflexed to approximately 90 degrees. With the hands stacked (middle fingertips aligned), the participant inhales, then exhales while hinging at the hips to reach forward toward the toes of the extended leg, avoiding bouncing; the back stays straight and the head upright. The maximal position is held for about 2 seconds. The linear distance between the tip of the middle finger and the toes of the extended leg is measured along the lower limb/foot.

Record the distance (cm) using the following convention-0 cm if fingertips just touch the toes; negative values if the fingertips do not reach the toes (gap); positive values if the fingertips reach past the toes (overlap). Perform two trials per leg; record the best value per leg.

The 30-Second Chair-Stand Test assesses functional muscular performance (strength × speed) of the lower extremities.

Stable, armless chair at approximately 46 cm seat height, placed against a wall to prevent movement. Participants wear non-slip, flat footwear or are barefoot. Participant sits upright, feet flat on the floor, arms crossed over the chest. On the assessor's signal, the participant stands up fully (knee and hip extension) and sits down as many times as possible within 30 seconds without using the arms. Count only full stand-sit cycles completed through the full range of motion (ROM). A repetition initiated in the final second (second 30) is counted as valid if more than 50% of the ROM is completed.

Number of valid chair-stands completed in 30 seconds. Minimum possible value is 0 repetitions; there is no predefined maximum. Higher values indicate better lower-extremity functional performance.

The Stand Up and Go Test assesses dynamic lower extremity power, dynamic balance, and overall functional mobility/coordination.

Stable chair placed against a wall, seat height approximately 43 cm; a cone/marker placed 2.4 m from the front edge of the chair; clear, unobstructed path.

Participant starts seated, back upright, feet flat on the floor. On the assessor's signal, the participant stands up, walks 2.4 m to the cone, turns around the cone, walks back to the chair, and sits down again. Timing begins on the start signal and stops when the participant is fully seated. Testing is performed in usual footwear; use of any assistive device (if permitted) should be consistent across visits and recorded.

Time to complete the task, measured in seconds (s) to at least 0.1 s precision. Minimum possible value is 0 s; there is no predefined maximum. Lower times indicate better mobility and balance (i.e., higher values indicate worse performance).

Body composition will be assessed using bioelectrical impedance analysis (seca Hamburg seca mBCA515), including measures of fat mass, lean body mass, body mass, and body water .

The investigators will consider changes in plasma concentrations of oxidative stress marker such as malondialdehyde.

The investigators will consider changes in plasma concentrations of inflammatory markers such as Interleukin 1 (IL-1), IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-alpha

RNA and DNA gene expression will be assessed in response to the interventions.

Chromosomal damage will be assessed in lymphocytes in response to the interventions.

Gene sequencing of the 16S rRNA on the stool samples are performed to identify the microbes down to genus level as well as the microbial diversity and relative abundance.

The stool short-chain fatty acids (SCFAs) will be extracted and quantitatively analysed by gas chromatography.

The metabolomic response (ie all metabolites) to the interventions will be analyzed using both nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques. Patterns of metabolites will be evaluated with statistical techniques, ie discriminant analysis and principal component analysis.

The plasma amino acid pattern will be assessed with HPLC-MS.

Evaluation of potential changes in nutritional habits (24 hours dietary recall) with GloboDiet

Sleep quality will be assessed using the Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI global score ranges from 0 to 21, with higher scores indicating worse sleep quality.

Quality of life will be assessed using the World Health Organization Quality of Life Questionnaire (WHOQOL). Scores range from 0 to 100, with higher scores indicating better perceived quality of life.