Dr. Gymbro
Fitness General Nutrition Recovery Science & Research Trending: supplements sports nutrition creatine pre workout recovery
A landscape editorial photograph with a modern, clean magazine feel, shot on a pale warm-gray concrete surface in soft natural window light from the left. In the foreground, two matte white ceramic espresso cups sit side by side. The left cup holds a small amount of dark espresso with golden crema. The right cup is filled twice as high. Beside them, two small stainless steel scoops hold fine coffee-colored powder, one half full and one heaped, suggesting a dose comparison without any text or labels. A pair of worn red leather boxing gloves rests slightly out of focus behind the cups, laces loosely draped, with a white hand wrap rolled neatly beside them. A minimalist digital kitchen scale in matte black sits at the edge of the frame, with a few roasted coffee beans scattered across the surface. In the soft-focus background, a boxing gym corner appears: a hanging heavy bag in muted charcoal, pale wood plank flooring, and a tall window with diffused morning light. The palette is warm cream, espresso brown, brick red, and soft slate gray, with gentle shadows and a shallow depth of field. The composition follows the rule of thirds, with the cups and scoops in the lower left third and open negative space on the right for headline overlay. The look is tactile and refined, like a high-end health and performance journal. It has natural grain, subtle contrast, and a calm, confident mood. There are no people, no text, no logos, and no futuristic elements.
Nutrition

Dupliranje doze kofeina jedva je pomoglo bokserima – što su pokazali rezultati

Dr. Gymbro · · 4 min read
#supplements #ergogenic aids #sports nutrition #pre workout #caffeine #boxing #power output

Mislite li da dvostruka doza pre‑treninga znači dvostruku izvedbu? Novo križano ispitivanje na 15 natjecateljskih boksera sugerira da to možda nije istina. Istraživači su usporedili 3 mg/kg i 6 mg/kg kofeina nasuprot placebu. Obje doze su poboljšale izvedbu skoka, a veća doza nije bila dosljedno bolja.

Što su istraživači zapravo učinili

Studija, objavljena u Journal of the International Society of Sports Nutrition (2026.) pod vodstvom Tuerhongjianga i suradnika, koristila je randomizirani, dvostruko‑slijepi, placebo‑kontrolirani križani dizajn. Sudjelovalo je petnaest muških boksera, svi na razini kineskog nacionalnog sportaša druge klase ili višoj.

Svaki bokser je prošao kroz tri uvjeta u nasumičnom redoslijedu, s tjednom pauzom između:

  • Placebo
  • 3 mg/kg kofeina (CAF3)
  • 6 mg/kg kofeina (CAF6)

Istraživački tim je mjerio kontramovinski skok (CMJ), balistički sklek (BPU) i izokinetički maksimalni moment (PT) dominantnog ramena i koljena. Testiranje je provedeno na bazalnoj razini i u blokovima koji su započeli 30 i 60 minuta nakon unosa. Statistika je koristila Holm‑prilagodbu kroz 10 unaprijed planiranih interakcijskih testova, čime se štiti od lažnih pozitivnih rezultata.

Glavni rezultat: obje doze su djelovale nakon 60 minuti

Na procjeni nakon 60 minuta, i 3 mg/kg i 6 mg/kg nadmašili su placebo po visini skoka, maksimalnoj snazi i relativnoj maksimalnoj snazi. Nije bilo značajne razlike između dviju doza kofeina.

Kod eksplozivnosti donjeg dijela tijela, manja doza je donijela mjerljivu korist. Udvostručenje doze nije dodalo ništa značajno na ovom testu.

Gdje je 6 mg/kg odskačio naprijed

Viša doza bila je bolja u nekoliko parametara:

  • Balistički sklek: CAF6 je proizveo veći koncentrični impuls, prosječnu i maksimalnu snagu u odnosu na placebo nakon 60 minuta. CAF3 nije pokazao razliku u odnosu na placebo.
  • Moment ekstenzije koljena: Ovo je najjasniji rezultat specifičan za dozu. CAF6 je nadmašio i placebo i CAF3 nakon 60 minuta.
  • Moment ramena: Fleksija i ekstenzija PT su porasli pod učincima kofeina u određenim vremenskim točkama, ali bez dosljedne prednosti veće doze.

Autori zaključuju da se obrazac odgovora razlikovao ovisno o dozi i zadatku te da 6 mg/kg nije dosljedno nadmašio 3 mg/kg. Veća doza donijela je nekoliko dodatnih „pobjeda“, ali ne opće poboljšanje.

Cheat sheet za mg‑po‑kg

Evo kako doze izgledaju u miligramima kofeina:

Tjelesna težina 3 mg/kg 6 mg/kg
60 kg (132 lb) 180 mg 360 mg
70 kg (154 lb) 210 mg 420 mg
80 kg (176 lb) 240 mg 480 mg
90 kg (198 lb) 270 mg 540 mg
100 kg (220 lb) 300 mg 600 mg

Provjerite etiketu svog pre‑treninga. Mnogi proizvodi navode 200–400 mg po porciji, a neki kombiniraju kofein s drugim stimulansima. Ako uzmete dvije porcije, kavu i energetsko piće, lako možete premašiti 6 mg/kg ne primjećujući to.

Vremenski okvir: ciljajte otprilike 60 minuta

Značajni učinci primijećeni su tijekom zakazanog 60‑minutnog bloka. To je optimalno vrijeme prema podacima iz studije, pa uzimanje kofeina otprilike sat vremena prije treninga najbolje se podudara s rezultatima. Sažetak naglašava 60‑minutni blok umjesto 30‑minutnog, stoga ne računajte na vrhunske benefite ako uzmete dozu neposredno prije početka treninga.

Zašto više nije nužno bolje

Studija nije u sažetku spomenula nuspojave, pa sljedeći podaci nisu rezultat ovog istraživanja, već općenite pozadine. Veće doze kofeina često su povezane s drhtavosti, anksioznošću, ubrzanim radom srca, probavnim smetnjama i poremećenom spavanjem. Za boksera pretjerana stimulacija može narušiti fokus i oporavak, a uzimanje navečer može ometati noćni odmor.

Ako 3 mg/kg pruža većinu mjerljivih koristi, prelazak na 6 mg/kg povećava rizik od nuspojava za ograničeni dodatni dobitak. Kompromis može imati smisla za određene ishode, poput momenta ekstenzije koljena, ali nije besplatna nadogradnja.

Za koga je ovo relevantno

  • Sportaši u snazi i borilačkim granama koji traže razumnu početnu dozu.
  • Teretani i rekreativci koji sumnjaju da je njihov pre‑trening jači nego što im treba.
  • Osobe osjetljive na kofein, koje imaju dobar razlog započeti s nižim rasponom.

Praktičan pristup: počnite blizu 3 mg/kg, uzmite ga otprilike sat vremena prije treninga i podižite dozu samo ako imate jasan razlog i dobro podnosite. Odgovor na kofein varira među pojedincima, stoga svaku dozu testirajte u treningu, a ne prvi put na natjecanju.

Ograničenja koja treba imati na umu

  • Udarac nije testiran. Autori napominju da su rezultati dokaz za odabrane neuromuskularne ishode, a ne izravni dokaz poboljšanja udarca ili kompetitivnog boksa.
  • Mali uzorak. Petnaest muških boksera je skroman broj i rezultati se možda ne primjenjuju na žene ili druge razine sportaša.
  • Laboratorijski testovi. Skokovi, sklekovi i izokinetički moment su kontrolirane mjere, a ne stvarna borba.
  • Mješoviti uzorak doza. Razlike između doza ovisile su o zadatku, a sažetak navodi da su klasifikacije individualnog odgovora istraživačke prirode.
  • Uobičajeni unos. Sažetak ne razmatra kako svakodnevna konzumacija kofeina može oblikovati odgovore, stoga osobnu toleranciju tretirajte kao otvoreno pitanje.

Zaključak

Kod treniranih boksera, 3 mg/kg kofeina poboljšalo je izvedbu skoka otprilike jednako kao i 6 mg/kg na 60‑minutnoj točki. Viša doza pokazala je prednosti samo kod nekih ishoda, posebno balističke snage sklekova i momenta ekstenzije koljena. Prije nego što udvostručite dozu, izračunajte svoj mg/kg, uzmite ga otprilike sat vremena prije treninga i zapamtite da nitko još nije dokazao kako se to prenosi na jači udarac.

Izvor: Tuerhongjiang et al. Acute effects of 3 and 6 mg·kg‑1 caffeine on strength‑power performance and isokinetic peak torque in competitive male boxers: a randomized, double‑blind, placebo‑controlled crossover trial. J Int Soc Sports Nutr. 2026. DOI: 10.1080/15502783.2026.2743368 | PubMed

Original study

Read the original research on pubmed.ncbi.nlm.nih.gov →

This article summarizes published research for general information. It is not medical advice.

Share XFacebookLinkedInRedditWhatsApp
DG

Written by

Dr. Gymbro

Dr. Gymbro writes for Dr. Gymbro: science-backed fitness, nutrition & performance.

Related Articles

A wide editorial still life on a pale, warm-toned concrete surface in soft morning window light. In the center-left, a shallow matte ceramic bowl holds a small pile of bright red coffee cherries with glossy skins, a few sliced open to reveal pale mucilage and paired green-tan beans. Beside it, a small glass dish of fine, golden-brown powdered extract with a tiny wooden scoop resting on its edge. A sprig of coffee plant leaves, deep green and waxy, arcs across the foreground. On the right side, slightly out of focus, a sleek road cyclist's handlebar and a matte black water bottle lean against a light plaster wall, suggesting athletic training without showing a person. A minimalist analog stopwatch with a clean white face and thin black hands sits in the mid-ground, angled toward the camera, its hands paused near the fifteen-minute mark. A folded linen cloth in oatmeal beige and a single small espresso cup with a thin crema ring add quiet texture. The color palette is restrained and modern: cherry red, sage green, cream, soft terracotta, and charcoal accents. Light comes from the left, casting long, gentle shadows with a subtle warm glow and a hint of dust in the air. Shallow depth of field with crisp focus on the cherries and stopwatch, creamy bokeh in the background. Composition leaves open negative space in the upper right for a headline overlay. The overall feel is a clean, trendy health-and-science magazine cover: tactile, natural, minimal, and calm, shot in a 16:9 landscape frame with fine film-like grain and true-to-life tones.
nutrition

Ekstrakt od kavevih bobica: 200 mg kaveina povećalo rad kod biciklista za 4,6 %

BY DR. GYMBRO ·

Niska doza od 200 mg kaveina iz ekstrakta cijele kaveve bobice pomogla je obučenim biciklistima da u 15‑minutnom testu proizvedu 4,6 % više rada. Ideja da takav ekstrakt ubrzava popunu glikogena u mišićima nije potkrijepljena podacima. Radi se o randomiziranom, dvostruko‑slijepom, križanom ispitivanju na 12 biciklista, financiranom od strane proizvođača. U tekstu su prikazani rezultati, ono što studija ne dokazuje i tko bi mogao imati korist od dodatka.
A sleek aluminum energy drink can and a matte scoop of white pre-workout powder sit side by side on a pale concrete gym bench, lit by soft morning window light. The can is slim and minimalist, with a muted sage green label and no legible text. Beside it is a clear glass shaker half full of cloudy, lightly frothy liquid with condensation beading on its surface. A few fine grains of powder are scattered across the bench, catching the light. Behind them, slightly out of focus, a stainless steel barbell rests on a rack, and a folded charcoal gym towel sits at the edge of the frame. The color palette is warm neutral: oatmeal, soft gray, and sage, with a single accent of pale citrus yellow from a halved lemon wedge placed near the glass. A thin, elegant shadow from the window blinds falls diagonally across the scene, giving it an editorial, magazine-style rhythm. The composition leaves generous negative space on the right third of the frame, a smooth blurred wall in warm off-white, suitable for headline text overlay. The shot is a low-angle, shallow depth-of-field product-style photograph, as if taken with an 85mm lens at f/2. The foreground objects are tack sharp and the background melts into creamy blur. The mood is calm, clean, and modern, like a wellness or science journal feature. Subtle film grain and gentle contrast add a tactile, contemporary lifestyle feel. There are no people, no logos, and no futuristic or sci-fi elements, just a quiet, considered still life that suggests the choice between a canned drink and a scooped supplement.
nutrition

Vaš energetski napitak može poslužiti kao pre‑workout — uz jedan uvjet

BY DR. GYMBRO ·

Kofein i taurina često se nalaze zajedno u energetskim napicima i pre‑workout suplementima, ali daje li to zaista bolji učinak? Meta‑analiza od 11 randomiziranih studija (ukupno 234 sudionika) pokazala je umjerena poboljšanja u maksimalnoj snazi i vremenu do iscrpljenosti, uz manji doživljaj napora. Srčani ritam se nije promijenio, a rezultat reakcijskog vremena bio je previše heterogen da bi dao pouzdane zaključke. Problem je u malom broju i veličini studija, pa je teško odrediti doprinos taurine izvan učinka kofeina.
A wide, editorial-style still life shot from a slightly elevated angle on a pale oak gym bench, bathed in soft morning window light. In the center sits a matte ceramic cup of black coffee with delicate steam curling upward, flanked by a small white scoop of coffee beans and two identical glass vials, one filled with a few grains of fine powder and one empty, hinting at dose comparison. Next to the cup rests a pair of worn white boxing hand wraps, loosely coiled, and a slim black stopwatch with its face softly visible. In the foreground, a minimalist notebook lies open with blurred handwritten numbers and a simple pen sketch of a bar graph with bars of equal height, subtle and unreadable, suggesting a null result without any legible text. A small brass kitchen scale sits to the side with a few coffee beans on its tray. In the soft-focus background, a boxing gym interior is visible: a hanging heavy bag in muted charcoal, exposed brick wall painted off-white, and tall windows casting long diagonal light across the floor. The color palette is warm and restrained: cream, sand, espresso brown, soft charcoal, with a single accent of muted terracotta orange in the hand wraps and a faint sage green in the notebook cover. Shallow depth of field with creamy bokeh, fine film grain, and gentle shadows give it a contemporary lifestyle-magazine and wellness-journal feel. The composition leaves generous negative space on the left third for headline overlay. Clean, calm, trendy, and tactile, with natural textures like wood grain, ceramic glaze, and cotton fabric. No people, no text, no futuristic elements.
science research

Kava s niskom dozom kofeina nije dala elitnim borcima nikakav poticaj za sprint

BY DR. GYMBRO ·

Mislite li da kava prije treninga daje dodatni zamah za sprintove? Nedavno je, u randomiziranom, dvostruko‑slijepom križanom ispitivanju na 15 nacionalnih boraca, otkriveno da ni jedna od doza kofeina (1,5 mg/kg i 3 mg/kg) ne donosi nikakvu prednost u izvedbi. Za sportaša od 68 kg to znači otprilike 100 mg i 200 mg kofeina. Vrhunac snage, prosječna snaga, indeks umora i čak procijenjeni doprinos energetskih sustava nisu se razlikovali od dekaf. Ipak, ovo je mali nul‑rezultat, a ne dokaz da kofein ne djeluje; većina pozitivnih studija koristi kapsule u rasponu 3–6 mg/kg. U nastavku su izračuni doze, upozorenja i savjeti za sljedeću napornu sesiju.
A wide, editorial-style flat lay photographed from slightly above on a pale oak gym bench with a soft matte finish. On the left, a small white ceramic cup of black coffee sits on a matching saucer, with a thin curl of steam rising and catching warm window light. Beside it is a second, slightly larger handleless stoneware mug in muted sage green, also filled with coffee, so the pair suggests one to two cups. In the center-right foreground rests a sleek matte-black steel barbell plate, partly overlapping a brushed-steel dumbbell with fine knurling. A folded charcoal gym towel and a clean white chalk-dusted wrist strap lie casually to one side. A small scatter of whole roasted coffee beans spills across the bench in front of the cups, glossy and deep brown. Near the bottom edge, a minimalist analog kitchen scale in soft cream with a thin black needle hints at precise dosing, without any readable numbers or text. Soft morning sunlight streams in from the upper left, creating long, gentle shadows and a warm golden glow against cool neutral tones. The background is a softly blurred, airy home gym or boutique training studio with out-of-focus squat rack uprights, pale concrete walls, and a leafy green plant in a terracotta pot adding a touch of organic color. The palette is restrained and modern: warm cream, espresso brown, charcoal, sage green, and hints of brushed silver. Shallow depth of field keeps the cups and beans tack sharp while the background melts into creamy bokeh. The composition leaves generous negative space on the right third for a title overlay, with a balanced, calm, premium magazine feel, like a contemporary wellness and sports science journal. High-resolution, natural color grading, subtle film grain, realistic textures on ceramic, steel, and coffee crema.
nutrition

Koliko Kofeina Prije Teretanja? Meta‑analiza Pokazuje da 1–2 mg/kg i dalje Djeluje

BY DR. GYMBRO ·

Standardni savjet za kofein prije teretanja iznosi 3–6 mg/kg, što je otprilike nekoliko šalica kave ili jedna velika doza pre‑workout dodatka. Meta‑analiza iz 2022. ., koja je obuhvatila 12 studija, otkrila je da i doze od 0,9–2 mg/kg poboljšavaju snagu (d ≈ 0,17), mišićnu izdržljivost (d ≈ 0,21) i prosječnu brzinu šipke (d ≈ 0,56). Za većinu dizača to je otprilike jedna do dvije šalice kave. Efekti su skromni i temelje se na akuta‑jednosesijskim istraživanjima, ali rezultati sugeriraju da istu korist možemo postići uz znatno manju količinu kofeina.

This page is available in

English العربيةবাংলাČeštinaDeutschEspañolفارسیFrançaisHausaहिन्दीHrvatskiBahasa IndonesiaItaliano日本語Basa Jawa한국어NederlandsਪੰਜਾਬੀPolskiPortuguêsRomânăРусскийSrpskiTürkçeУкраїнськаTiếng Việt中文