Thoob plaws keeb kwm, lub ntsiab lus ntawm ib tug txiv neej tau txuas nrog nws cov tshuaj hormones txiv neej tseem ceeb testosterone. Thaum muaj hnub nyoog li ntawm 30 xyoo, cov testosterone pib poob qis thiab qhov no tuaj yeem ua rau muaj ntau yam kev hloov pauv tsis zoo rau nws lub cev thiab kev noj qab haus huv: txo qis kev ua haujlwm ntawm kev sib deev, qis zog, txo cov leeg nqaij thiab nce rog, thiab lwm yam.
Ua ke nrog cov pa phem ib puag ncig, kev ntxhov siab thiab kev noj zaub mov tsis zoo uas feem ntau tshwm sim hauv peb lub neej thiab nws tsis yog qhov xav tsis thoob uas peb pom muaj kev sib kis ntawm cov testosterone qis hauv cov txiv neej thoob plaws ntiaj teb.
Xyoo 2013, ib pawg kws tshawb fawb Kauslim tau kawm txog qhov cuam tshuam ntawm kev raug rau noob qes raulub teeb liab (670nm) thiab lub teeb infrared (808nm).
Cov kws tshawb fawb tau muab 30 tus nas txiv neej faib ua peb pawg: ib pawg tswj thiab ob pawg uas raug lub teeb liab lossis lub teeb infrared. Thaum kawg ntawm 5 hnub sim uas cov nas raug kev kho mob ib zaug 30 feeb hauv ib hnub, pawg tswj tsis pom muaj kev nce ntxiv ntawm testosterone thiab cov theem testosterone hauv ob qho tib si nas liab thiab infrared tau pom tias muaj kev nce siab ntau:
"... Qib T hauv cov ntshav tau nce ntxiv ntau heev hauv pawg 808nm wavelength. Hauv pawg 670 nm wavelength, qib T hauv cov ntshav kuj tau nce ntxiv ntau heev rau cov testosterone ntawm tib lub zog ntawm 360 J/cm2/hnub."