## 1 Introduction  
The adapted moderate training exercise (AMTE), corresponding to the adapted nonexhaustive aerobic physical activity is an exciting approach, is increasingly considered by the scientific community to prevent metabolic disabling diseases and increase physical well-being. Data from the literature show that moderate physical activity can reduce inflammation and improve general physical function in humans [1; 2; 3; 4; 5; 6; 7; 8; 9] and animals [10; 11]. In a rat model, aerobic interval exercise protocol was shown to prevent the development of diabetic nephropathy and to affect the metabolism of certain minerals [12]. Moreover, aerobic training in association with L-arginine supplementation also demonstrated to ameliorate kidney and liver damage in myocardial infarction rats, via antioxidant mechanisms [13]. The expression of many cytokines and adipokines associated with metabolic syndrome has also been investigated in obese women, after aerobic training protocol, with positive results [14]. In recent literature, authors described that AMTE has beneficial effects on the preservation of articular cartilage and muscle tissues, confirming its protective role on the musculoskeletal system as well [15; 16; 17; 18]. Neutrophil gelatinase-associated lipocalin (NGAL) is a small protein of the lipocalin superfamily, also known as lipocalin-2 [19]. It is physiologically and basally present at low levels in many tissues including heart, kidney, liver, uterus, bone marrow, lung, adipose tissue, and macrophages [20; 21; 22]. Its upregulation follows the activation of the NF-kB pathway [23]. NGAL was shown to play a pivotal role as a modulator of the innate immune system in inflammation [24; 25; 26]. Of note, the complex NGAL-MMP-9 extends the proteolytic activity of the latter by inhibiting its degradation [27], which leads to several pathophysiological conditions [28]. In human diseases, several studies have shown that NGAL increases significantly and rapidly in case of renal cell damage, suggesting that NGAL is a biomarker of various forms of kidney injuries [29; 30]. NGAL upregulation could also be a biomarker in patients who suffer from heart failure [31] or in those who undergo cardiac surgery [32]. NGAL is upregulated in several other inflammatory states, like chronic obstructive pulmonary disorder and bowel inflammatory condition [33]. Strenuous exercise, causing oxidative stress and reactive oxygen species (ROSs) production, can induce changes in NGAL concentration as well [34; 35; 36]. [PERSON] et al. reported that prolonged endurance exercise in healthy adults could induce an increase in NGAL urinary concentration [34]. Increased NGAL urinary levels have also been found in endurance cycling athletes [35]. These findings were validated by [PERSON] et al., who demonstrated increased acute expression of serum NGAL in long distance running athletes (strenuous exercise) [36]. The expression of NGAL has also been investigated in physically active individuals, after short-term maximal exercise, but no differences in its expression have been reported [37; 38]. However, the expression of NGAL in association with an AMTE protocol has never been investigated. Another, recently emerging important compound positively associated with physical activity is represented by vitamin D. It is a fat-soluble molecule able to exert antioxidant functions, responsible for the body's mineral homeostasis. This vitamin can be taken exogenously with food or endogenously produced by the skin during the exposure to sunlight. After synthesis, vitamin D is inactive. The liver operates the conversion from the inactive form to 25-hydroxyvitamin D or calcidiol by hydroxylation at carbon 25. The latter is then collected in the adipose tissue as a reserve. To become active, 25-hydroxyvitamin D needs the participation of kidneys and 1-hydroxylase enzyme to be converted into 1,25-dihydroxyvitamin D, known as calcitriol [39]. The body cells respond to vitamin D in its active form through its receptor called vitamin D receptor (VDR) [40].